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Homeric Odyssey
2006-04-25 22:59
by Mike Carminati

Last night, I ran across an article on Yahoo saying that home runs are up this year (and not just in Jim Thome's stat line).

Then I moseyed to ESPN and was told that an AP-AOL Sports poll found that 53 percent of baseball fans feel that "Baseball has fallen short on keeping the sport drug-free." They also found that two-thirds of fans are down on Barry Bonds though more than half would still put him in the Hall of Fame.

To quote my dad, "What the hex!" What's going on here?

The fans are correct in being suspicious of baseball's intentions where it comes to a drug policy. Both the players union and the owners profited by the inflated offensive numbers of the past dozen or so years. Both were slow to address the issue, but they now have a policy that appears effective. I mean, at least there have been a handful of minor leaguers already suspended for almost a full season (100 games).

But some will question why home runs are up if the drug policy is working so well? Oddly, those are the same people rejoicing over Barry Bonds' painfully slow start this year. I have trouble with this sort of cognitive dissonance myself.

Then again, there's the next level of cynics who say that the drug testing is academic since major-league players have switched to untraceable types of enhancements like HGH (Human Growth Hormone) or prolonged sessions on Howard Stern's sybean [sp?]. Minor-leaguers get caught using steroids because they can't afford the good stuff.

Finally, your trek through the baseball cognoscenti caste system, you will reach nirvana. That is, you will realize that there are many, many other factors that have conspired to prolong the home run inflation.

Expansion and tinkering with the strike zone and the ball have all been factors. However, in my opinion, the largest factor is the high turnover in baseball stadiums, usually from the old standard tin can-type parks to today's revenue-generating bandboxes. The new stadium boom, you might notice, coincides almost perfectly with the current offensive boom.

OK, so it's just a theory, but maybe we can test it…

First, let's verify that there is an issue. The numbers look impressive in the Yahoo article, but what do they mean? Let's look at the numbers for Aprils in the last twenty years and see what they mean as compared to the season as a whole (current stats through last night's games, for all years stats are through April and may include March stats):

YrApril HRApril ABApril HR/ABHRABHR/ABApr/Tot
Grand Total116264063632.86%8395529079692.89%99.10%

Balls are flying out of the ballpark more quickly (i.e., in 3.52% of all at-bats) than in any other full season. However, April 2006 ranks behind 2000 and is just ahead of 2001. In those seasons, homers fell sharply after April.

However, on average April home run rates are slightly below the season average (i.e., at 99.10%). One would expect if this holds true that then homers will comprise 3.55% of all at-bats by season's end, the highest percentage ever.

Ok, so there seems to be a potential issue here, but could this season just be an aberration? Homers had been falling in previous seasons, right?

Well, yes, home runs were slightly down last season, but it wasn't 1968 or anything. Besides slight downturns happen, how does the current decade compare with the past? Let's see…


So where's the change coming from? St. Louis has a new ballpark. Could that be skewing the data?

Here is a comparison over the last two seasons of ballpark factors using data (based on PF = ((homeRS + homeRA)/(homeG)) / ((roadRS + roadRA)/(roadG))). The table is split to fit in the column:

Team2006 ParkRunsHRH2B3BBB
ArizonaChase Field 1.4322.1671.2440.8642.0001.014
San DiegoPETCO Park 1.0481.4141.0930.7380.7500.860
HoustonMinute Maid Park 1.1511.7461.0130.7820.3571.107
ClevelandJacobs Field 1.0691.2841.0091.1221.4441.152
ChicagoWrigley Field 0.8351.4290.8760.8080.6290.992
PittsburghPNC Park 1.1751.2181.0450.9310.3001.258
AtlantaTurner Field 0.7731.1951.0401.2310.9290.587
DetroitComerica Park 1.1391.2171.1251.0451.4861.026
BaltimoreCamden Yards 1.2411.2041.1741.9180.8080.769
TexasAmeriquest Field 1.0301.4641.0841.1310.8180.926
NY MetsShea Stadium 1.0330.9950.9431.4550.4850.909
SeattleSafeco Field 0.8190.9620.8890.5380.8751.044
Kansas CityKauffman Stadium 0.9830.8751.1331.5911.1250.637
OaklandMcAfee Coliseum 1.1901.0001.0131.2330.4441.067
NY YankeesYankee Stadium 1.2281.1161.0180.8200.4581.281
BostonFenway Park 0.8690.8140.8741.5680.9000.725
CinicinnatiGreat American Ball Park1.5311.1861.3271.4610.4071.176
San FranciscoAT&T Park 1.2820.8250.9781.5310.5711.166
WashingtonRFK Stadium 0.7420.6840.9160.9735.0560.636
FloridaDolphin Stadium 0.9250.7050.8510.9172.7501.369
Tampa BayTropicana Field 0.8930.7670.8570.6393.4291.447
MilwuakeeMiller Park 0.7330.8860.7810.7502.4551.171
St.LouisBusch Stadium (III)1.0750.9411.0130.8761.3500.946
MinnesotaMetrodome 1.1800.7311.0671.2002.0001.300
LA of AnaheimAngel Stadium 0.7320.6550.8900.8862.4760.929
Chi White SoxU.S. Cellular Field 0.9111.0640.9150.6360.1461.182
TorontoRogers Centre 0.9430.9351.0670.7951.6360.786
ColoradoCoors Field 0.8710.7781.0140.7550.8331.264
PhiladelphiaCitizens Bank Park 0.8820.6840.8621.2610.3001.258
LA DodgersDodger Stadium 0.7570.3730.8381.0620.3331.123

Now last year's data with the difference between the two:

Team2005 ParkRunsHRH2B3BBBHR DiffR Diff
ArizonaChase Field 1.0781.0461.0451.0691.6591.0411.1210.354
San DiegoPETCO Park 0.8030.7500.9030.8321.3310.9450.6640.245
HoustonMinute Maid Park 0.9491.1950.9900.8040.9260.9710.5510.202
ClevelandJacobs Field 0.8800.8720.9231.0430.3381.0040.4120.189
ChicagoWrigley Field 1.0151.0521.0091.0581.0860.9540.377-0.180
PittsburghPNC Park 1.0340.8681.0581.1251.3381.0180.3500.141
AtlantaTurner Field 1.0950.8791.0611.1201.3991.0140.316-0.322
DetroitComerica Park 0.9590.9441.0380.8871.7371.0410.2730.180
BaltimoreCamden Yards 0.8760.9610.9430.8240.6811.2140.2430.365
TexasAmeriquest Field 1.0761.2631.0361.0321.8120.9750.201-0.046
NY MetsShea Stadium 0.9630.8711.0050.9520.6861.0130.1240.070
SeattleSafeco Field 0.9700.8441.0200.9620.6081.0490.118-0.151
Kansas CityKauffman Stadium 0.9720.7611.0221.1570.9120.9880.1140.011
OaklandMcAfee Coliseum 1.0640.8901.0151.1270.7820.9800.1100.126
NY YankeesYankee Stadium 1.0511.1061.0830.8821.1220.8910.0100.177
BostonFenway Park 1.0270.8860.9641.3240.8901.076-0.072-0.158
CinicinnatiGreat American Ball Park1.1281.2631.0701.1870.5300.958-0.0770.403
San FranciscoAT&T Park 0.9700.9150.9630.9081.0440.974-0.0900.312
WashingtonRFK Stadium 0.8600.7750.8510.8881.0510.953-0.091-0.118
FloridaDolphin Stadium 0.8830.8030.9250.8591.0951.114-0.0980.042
Tampa BayTropicana Field 0.9860.8761.0010.9041.2660.991-0.109-0.093
MilwuakeeMiller Park 0.9921.0850.8950.8770.9481.032-0.199-0.259
St.LouisBusch Stadium (II)1.0281.1481.0151.0620.6280.992-0.2070.047
MinnesotaMetrodome 1.0190.9470.9720.9670.8280.897-0.2160.161
LA of AnaheimAngel Stadium 0.9210.9010.9510.9840.9880.983-0.246-0.189
Chi White SoxU.S. Cellular Field 1.0441.3750.9720.9230.8641.086-0.311-0.133
TorontoRogers Centre 1.0391.2551.0451.0711.0850.882-0.320-0.096
ColoradoCoors Field 1.2851.1191.2541.1351.4811.035-0.341-0.414
PhiladelphiaCitizens Bank Park 1.1611.2891.1171.1271.4060.931-0.605-0.279
LA DodgersDodger Stadium 0.9011.0490.9040.9770.4161.042-0.676-0.144

What happened to Coors? And moving the left field back two feet in Philly really mattered? Hmm… And what happened to PETCO and the BOB, former pitcher's parks?

Could it be this is what happens when you use a small sample of data, like what we have so far? Sure, but I'm too impatient to wait for the season's end.

Do stadiums really change that much from year to year? Well, for historic ballpark data we are left with lahman data, which unfortunately uses a different format from ESPN. However it is useful for looking at annual changes to data.

Here are the greatest increasex in ballpark factor (BPF) from a previous season. You'll notice new ballparks are a factor:

TeamYrParkBPFPrev YrParkBPFDiff
Cincinnati Reds1902Palace of the Fans1101901League Park II in Cincinnati9317
Montreal Expos2003Stade Olympique/Hiram Bithorn Stadium1182002Stade Olympique10117
Cincinnati Reds2005Great American Ball Park1062004Great American Ball Park9214
New York Yankees2000Yankee Stadium II1041999Yankee Stadium II9113
Houston Astros2000Enron Field1071999Astrodome9413
Texas Rangers2002The Ballpark at Arlington1122001The Ballpark at Arlington10012
Colorado Rockies1995Coors Field1281994Mile High Stadium11612
Troy Trojans1880Haymakers' Grounds1051879Putnam Grounds9312
Chicago Cubs1916Wrigley Field1111915West Side Park II10011
Baltimore Orioles1883Oriole Park1031882Newington Park9211
Milwaukee Brewers1994County Stadium1051993County Stadium9510
Colorado Rockies1999Coors Field1291998Coors Field11910
Pittsburgh Pirates1891Exposition Park981890Recreation Park8810
Baltimore Orioles2004Oriole Park at Camden Yards1042003Oriole Park at Camden Yards959
Cincinnati Reds2002Cinergy Field1082001Cinergy Field999

Now, here are the greatest decreases:

TeamYrParkBPFPrev YrParkBPFDiff
Montreal Expos2004Stade Olympique/Hiram Bithorn Stadium952003Stade Olympique/Hiram Bithorn Stadium118-23
St. Louis Browns1892Sportsman's Park I951891Sportsman's Park I115-20
Hartford Dark Blues1877Union Grounds (Brooklyn)891876Hartford Ball Club Grounds108-19
Kansas City Royals2004Royals Stadium952003Royals Stadium113-18
Newark Pepper1915N/A941914N/A111-17
Chicago Cubs2000Wrigley Field901999Wrigley Field107-17
Los Angeles Dodgers1962Dodger Stadium941961Los Angeles Memorial Coliseum109-15
Los Angeles Angels1962Dodger Stadium971961Wrigley Field (LA)111-14
Seattle Mariners2000Safeco Field911999Kingdome / Safeco Field103-12
Oakland Athletics2003Oakland Coliseum932002Oakland Coliseum104-11
Philadelphia Phillies1938Baker Bowl/Shibe Park971937Baker Bowl108-11
Brooklyn Atlantics1874Union Grounds881873Union Grounds99-11
Troy Trojans1882Troy Ball Clubs Grounds951881Haymakers' Grounds105-10
St. Louis Maroons1885Sportsman's Park I941884N/A104-10
Baltimore Orioles2005Oriole Park at Camden Yards942004Oriole Park at Camden Yards104-10
Anaheim Angels2002Edison International Field972001Edison International Field107-10

Let's just look at stadium changes (i.e., not just stadium name changes). I'm including all new stadiums since the dawn of time since I love this stuff:

TeamYrParkBPFPrev YrParkBPFDiff
Washington Nationals2005R.F.K. Stadium932004Stade Olympique/Hiram Bithorn Stadium95-2
Philadelphia Phillies2004Citizen's Bank Park1012003Veterans Stadium956
San Diego Padres2004Petco Park922003Qualcomm Stadium911
Montreal Expos2003Stade Olympique/Hiram Bithorn Stadium1182002Stade Olympique10117
Cincinnati Reds2003Great American Ball Park1002002Cinergy Field108-8
Milwaukee Brewers2001Miller Park1012000County Stadium965
Pittsburgh Pirates2001PNC Park1002000Three Rivers Stadium982
Houston Astros2000Enron Field1071999Astrodome9413
San Francisco Giants2000PacBell Park9119993Com Park892
Detroit Tigers2000Comerica Park971999Tiger Stadium101-4
Seattle Mariners2000Safeco Field911999Kingdome / Safeco Field103-12
Seattle Mariners1999Kingdome / Safeco Field1031998Kingdome1003
Atlanta Braves1997Turner Field1021996Atlanta-Fulton County Stadium106-4
Colorado Rockies1995Coors Field1281994Mile High Stadium11612
Texas Rangers1994The Ballpark at Arlington1001993Arlington Stadium964
Cleveland Indians1994Jacobs Field1001993Cleveland Stadium1000
Baltimore Orioles1992Oriole Park at Camden Yards1031991Memorial Stadium967
Chicago White Sox1991Comiskey Park II981990Comiskey Park980
Toronto Blue Jays1990Skydome1021989Exhibition Stadium /Skydome984
Toronto Blue Jays1989Exhibition Stadium /Skydome981988Exhibition Stadium100-2
Minnesota Twins1982Hubert H Humphrey Metrodome1031981Metropolitan Stadium107-4
Montreal Expos1977Stade Olympique971976Jarry Park104-7
New York Yankees1976Yankee Stadium II991975Shea Stadium972
New York Yankees1974Shea Stadium971973Yankee Stadium I970
Kansas City Royals1973Royals Stadium1081972Municipal Stadium II1008
Texas Rangers1972Arlington Stadium961971R.F.K. Stadium942
Philadelphia Phillies1971Veterans Stadium1001970Connie Mack Stadium973
Pittsburgh Pirates1971Three Rivers Stadium1001970Forbes Field/Three Rivers Stadium982
Cincinnati Reds1971Riverfront Stadium981970Crosley Field/Riverfront Stadium100-2
Milwaukee Brewers1970County Stadium1011969Sicks Stadium983
Pittsburgh Pirates1970Forbes Field/Three Rivers Stadium981969Forbes Field980
Cincinnati Reds1970Crosley Field/Riverfront Stadium1001969Crosley Field105-5
Oakland Athletics1968Oakland Coliseum951967Municipal Stadium I97-2
St. Louis Cardinals1967Busch Stadium II991966Sportsman's Park IV/Busch Stadium II101-2
Atlanta Braves1966Atlanta-Fulton County Stadium1021965County Stadium1011
California Angels1966Anaheim Stadium971965Dodger Stadium98-1
St. Louis Cardinals1966Sportsman's Park IV/Busch Stadium II1011965Sportsman's Park IV109-8
Houston Astros1965Astrodome931964Colt Stadium94-1
New York Mets1964Shea Stadium981963Polo Grounds IV102-4
Washington Senators1962R.F.K. Stadium991961Griffith Stadium II990
Los Angeles Angels1962Dodger Stadium971961Wrigley Field (LA)111-14
Los Angeles Dodgers1962Dodger Stadium941961Los Angeles Memorial Coliseum109-15
Minnesota Twins1961Metropolitan Stadium1061960Griffith Stadium II997
San Francisco Giants1960Candlestick Park941959Seals Stadium98-4
San Francisco Giants1958Seals Stadium981957Polo Grounds IV100-2
Los Angeles Dodgers1958Los Angeles Memorial Coliseum1031957Ebbets Field110-7
Washington Senators1956Griffith Stadium II1001955Griffith Stadium I955
Kansas City Athletics1955Municipal Stadium I1011954Connie Mack Stadium1001
Baltimore Orioles1954Memorial Stadium931953Sportsman's Park IV102-9
Milwaukee Braves1953County Stadium941952Braves Field97-3
Cleveland Indians1947Cleveland Stadium971946League Park II/Cleveland Stadium943
Philadelphia Phillies1939Shibe Park971938Baker Bowl/Shibe Park970
Philadelphia Phillies1938Baker Bowl/Shibe Park971937Baker Bowl108-11
Boston Red Sox1934Fenway Park II1071933Fenway Park I998
Cleveland Indians1932League Park II/Cleveland Stadium1071931League Park II1061
New York Yankees1923Yankee Stadium I1021922Polo Grounds IV1020
St. Louis Cardinals1921Sportsman's Park IV981920Robison Field/Sportsman's Park IV962
St. Louis Cardinals1920Robison Field/Sportsman's Park IV961919Robison Field942
Chicago Cubs1916Wrigley Field1111915West Side Park II10011
Boston Braves1916Braves Field961915Fenway Park I / Braves Field960
Boston Braves1915Fenway Park I / Braves Field961914South End Grounds III99-3
Brooklyn Superbas1913Ebbets Field1031912Washington Park III967
New York Yankees1913Polo Grounds IV1001912Hilltop Park106-6
Boston Red Sox1912Fenway Park I1051911Huntington Avenue Grounds996
Cincinnati Reds1912Crosley Field971911Palace of the Fans961
New York Giants1912Polo Grounds IV1031911Polo Grounds III/Polo Grounds IV1030
Detroit Tigers1912Navin Field971911Bennett Park105-8
New York Giants1911Polo Grounds III/Polo Grounds IV1031910Polo Grounds III1003
Washington Senators1911Griffith Stadium I981910American League Park II953
Chicago White Sox1911Comiskey Park971910South Side Park II/Comiskey Park961
Chicago White Sox1910South Side Park II/Comiskey Park961909South Side Park II960
Pittsburgh Pirates1910Forbes Field1061909Exposition Park/Forbes Field108-2
Cleveland Naps1910League Park II1011909League Park I104-3
Pittsburgh Pirates1909Exposition Park/Forbes Field1081908Exposition Park1008
Philadelphia Athletics1909Shibe Park1021908Columbia Park107-5
St. Louis Browns1909Sportsman's Park IV931908Sportsman's Park III101-8
Washington Senators1904American League Park II981903American League Park I102-4
New York Highlanders1903Hilltop Park1061902Oriole Park1042
Cincinnati Reds1902Palace of the Fans1101901League Park II in Cincinnati9317
St. Louis Browns1902Sportsman's Park III991901Lloyd Street Grounds954
Brooklyn Bridegrooms1898Washington Park III1001897Eastern Park955
Philadelphia Phillies1895Baker Bowl1001894Philadelphia Baseball Grounds973
Boston Beaneaters1895South End Grounds III1081894South End Grounds II / Congress Street Grounds / South End Grounds III1080
Chicago Colts1894West Side Park II1051893South Side Park I996
Cincinnati Reds1894League Park II in Cincinnati1041893League Park I in Cincinnati1022
Boston Beaneaters1894South End Grounds II / Congress Street Grounds / South End Grounds III1081893South End Grounds II1080
St. Louis Browns1893Robison Field1001892Sportsman's Park I955
Louisville Colonels1893Eclipse Park II921892Eclipse Park I920
Pittsburgh Pirates1891Exposition Park981890Recreation Park8810
Cleveland Spiders1891League Park I1041890National League Park986
Brooklyn Grooms1891Eastern Park991890Washington Park II100-1
New York Giants1891Polo Grounds III961890Polo Grounds II100-4
Chicago Colts1891South Side Park I1001890West Side Park I104-4
Baltimore Orioles1891Union Park1011890Oriole Park105-4
Brooklyn Bridegrooms1890Washington Park II1001889Washington Park I1000
Cleveland Spiders1889National League Park981888National League Park II971
New York Giants1889Polo Grounds II1001888Polo Grounds I991
Kansas City Cowboys1889Exposition Park1061888Association Park I1060
Indianapolis Hoosiers1888Athletic Park II1021887Athletic Park I966
Boston Beaneaters1888South End Grounds II1021887South End Grounds I1002
Philadelphia Quakers1887Philadelphia Baseball Grounds1061886Recreation Park1015
New York Metropolitans1886St. George Cricket Grounds961885Polo Grounds I West Diamond924
Chicago White Stockings1885West Side Park I1151884Lake Front Park II1087
Pittsburgh Alleghenys1884Recreation Park1021883Exposition Park I957
Buffalo Bisons1884Olympic Park I1031883Riverside Park1021
Cincinnati Red Stockings1884League Park I in Cincinnati1051883Bank Street Grounds106-1
Baltimore Orioles1883Oriole Park1031882Newington Park9211
Chicago White Stockings1883Lake Front Park II1061882Lake Front Park I/Lake Front Park II1051
Philadelphia Athletics1883Jefferson Street Grounds1081882Oakdale Park112-4
Chicago White Stockings1882Lake Front Park I/Lake Front Park II1051881Lake Front Park I1050
Troy Trojans1882Troy Ball Clubs Grounds951881Haymakers' Grounds105-10
Troy Trojans1880Haymakers' Grounds1051879Putnam Grounds9312
Cincinnati Reds1880Bank Street Grounds991879Avenue Grounds954
Chicago White Stockings1878Lake Front Park I107187723rd Street Grounds112-5
Hartford Dark Blues1877Union Grounds (Brooklyn)891876Hartford Ball Club Grounds108-19
Brooklyn Atlantics1873Union Grounds991872Capitoline Grounds104-5

Now, here are stadiums for new ballclubs since 1901:

Arizona Diamondbacks1998Bank One Ballpark101
Tampa Bay Devil Rays1998Tropicana Field104
Florida Marlins1993Joe Robbie Stadium102
Colorado Rockies1993Mile High Stadium120
Seattle Mariners1977Kingdome99
Toronto Blue Jays1977Exhibition Stadium101
Kansas City Royals1969Municipal Stadium II101
Seattle Pilots1969Sicks Stadium98
Montreal Expos1969Jarry Park100
San Diego Padres1969Jack Murphy Stadium96
New York Mets1962Polo Grounds IV102
Houston Colt .45's1962Colt Stadium93
Washington Senators1961Griffith Stadium II99
Los Angeles Angels1961Wrigley Field (LA)111
Chicago Chi-Feds1914Wrigley Field94
Chicago White Sox1901South Side Park II97
Boston Americans1901Huntington Avenue Grounds98
Milwaukee Brewers1901Lloyd Street Grounds95
Detroit Tigers1901Bennett Park105
Cleveland Blues1901League Park I96
Philadelphia Athletics1901Columbia Park104
Baltimore Orioles1901Oriole Park104
Washington Senators1901American League Park I99

You'll note that almost all of the new stadiums in the last 15 seasons have had ballparks that have BPFs greater than the league average. You may also notice that some parks have more ups and downs than Jason Giambi on a rollercoaster. I thought it might be fun to look at the standard deviation and variance for BPFs:

Std Dev Var
DecadeBPFPrev BPFDiffBPFPrev BPFDiff

I think a couple of things are happening: As more homers are hit, the variation among team stadiums as well as for a given stadium from year to year goes up just because we're dealing with bigger numbers.

The other thing is that teams are building a number of idiosyncratic stadiums, and as each is built a cookie-cutter tin can stadium bids adieu. With the old Busch gone, Shea's the last one left, right? These throwback stadiums create throwback instability. This decade's BPF changes are closer to the 1890s than the 1990s.

The end result? Get used to the homers, and don't expect that a hitter's park one year will necessarily be one the next. Is it steroid use? Doubtful. Oh, and get off Barry Bonds' back.

2006-05-02 10:52:10
1.   dmac
I'd just like to say that "Palace of the Fans" might be the coolest stadium name ever.

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