Leonard Koppett, the author of the incomparable (New) Thinking Fan's Guide to Baseball and 24 Seconds to Shoot (about some other sport), has an interesting, if short column in the Seattle Post-Intelligencer today. Koppett unearths a quote about the DH being the ruination of NL starters from the November 1, 1974 edition of the NY Daily News:
"The National League's persistent refusal to endorse the designated hitter gimmick is causing a statistical imbalance that will generate future repercussions as far away as the Cooperstown Hall of Fame."
Koppett goes on to demonstrate that the AL's alleged hegemony in starting pitching did not last long. Complete games, the number of 20-game winners, and the number of 300-inning pitchers evened out over time. Besides as Koppett points out "complete games and 300 innings aren't good [indicators of excellence] under the conditions of the last 20 years" and "you shouldn't try to draw long-range conclusions from two-year samples, or assume voters are too dumb to make sensible evaluations."
The Daily News writer in 1974 had no one of knowing that five-man rotations and the growth and (over)use of bullpens/closers would obviate the use of complete games and 300-inning pitchers as indicators of pitching excellence. ERA became more important, and now thanks to Baseball-Reference.com, ERA above the park-adjusted average becomes an excellent tool for evaluating starters.
Of course, when I was growing up in the mid-Seventies, the NL was known for its great power pitching (Seaver, Carlton, etc.). The assumption, whether true or not, was that the AL had more junk-ballers. This runs at odds with the 1974 article.
Today, there are great starters throughout the majors. Of course, the short-lived disparity from 1974 would even out over time as competition drove all teams to improve and as the game evolved so that the metrics concerned no longer have the same connotation.
Consider that one of the greatest pitchers of the last 15 years, Greg Maddux, has only won 20 games twice, never broke 270 innings in a season, and never had more than 10 complete games in a season. However, Maddux is all but enshrined in Cooperstown already. It seems that the Hall voters and the public in general has gotten over their infatuation with these once-sacrosanct statistics.