Well, I finally saw the play on Sports Center and it was even more of a mess than I was lead to believe in the press. Here's what I saw:

- The fly ball was maybe a third of the way between homeplate and the mound, and it was maybe 2-3 feet towards the third base line.

- It was clearly Michael Barrett's ball. He came out from behind the plate, stopped, and appeared to look at Fernando Tatis, the third baseman. It seemed like he expected Tatis to make the play.

- It is my understanding that on balls hit in this area, it is the pitcher's job to call who will get the ball. I did not see any signal by anyone let alone the pitcher (though I may have missed it).

- Tatis hesitated, probably thinking that it was Barrett's ball, and then lunged for the ball and missed.

- Barrett picked up the ball and stepped on home, and then the three Expos huddled a few feet from home in fair territory. Apparently they thought there was now two outs with the bases loaded and were discussing what to do next. Or perhaps they were still trying to figure out the play.

- In any case no one bothered with Neifi Perez who sheepishly walked towards home from third and touched home. I'm not sure if Perez knew what was going on and was waiting until Barrett was far enough from home for him to score or if he just realized that the most prudent choice would be to touch home given the confusion and then let the umps sort it out later.

- Perez's scoring seemed an annoyance more than anything else to the Expos. Tatis then touched home as if to force Perez who had already crossed the plate or to enforce the fact that they had already tagged or maybe he thought that he could retire the next baserunner on a force at home.

- When they were informed that Perez and really and truly scored, they were quite upset until Robinson came out and barked in apparent disgust for them to cease and desist.

So Perez did not tag up as the AP had said. He was clearly off the third base bag when the ball dropped in, and he did not bother to retreat to third to tag. He just slowly "excuse me"'d his way across the plate.

Here are some illumintaing anecdotes from Rich Marazzi's The Rules and Lore of Baseball:

It should be understood that if a runner advances at his own risk, the fielders are required to tag the runner. Gene Freese, Ron Santo, and Ken Boyer each had to learn this rule the hard way.

Confusion over this aspect of the infield fly caused a problem in the Cub-Cardinal game played on July 25, 1961.

Ron Santo was on second and Jerry Kindall on first for the Cubs, in the second inning, when Ed Bouchee popped to second baseman Julian Javier. As there were less than two out, the infield fly rule was in effect, and Bouchee was out according to the rule.

Javier dropped the ball, and, as the rule states, Santo was free to advance at his own peril. Javier recovered the ball and threw to Ken Bayer, who stepped on third base. The force play was not in order, but Santo, believing he had been retired, started toward the dugout; Cardinal pitcher Ray Sadecki yelled to Boyer, who tagged Santo when the Cub runner attempted to return to the bag.

This next situation was created in the first game of a double-header between the Braves and Pirates at Milwaukee on June 3, 1956.

With none out in the Milwaukee half of the ninth inning and Braves on first and second, Frank Torre hit a fly to short center field. Either shortstop Dick Groat or center fielder Bill Virdon could have caught the ball. But when Groat got under it, umpire Augie Donatelli signaled that Torre was automatically out under the infield fly rule. Groat, however, dropped the ball, and the confusion began. Former Dodger slayer Bobby Thomson, who was on second base, forgot that Torre was automatically out and headed for third, thinking a force play was in effect. The throw beat Thomson to third, but Gene Freese, the Pirate third sacker, also committed a mental error, stepping on the bag instead of tagging Thomson, who was then safe at third. Bill Bruton, the runner on first, advanced to second in the confusion. During the Pirates' argument that ensued, catcher Hank Foiles was banished.

Among other things, the odd play created an official scoring problem. The error originally was charged to Freese because of his failure to tag Thomson. It was transferred to Groat, however, since his failure (deliberate or otherwise) to catch the ball had induced the base runners to try to advance, and since Freese's mistake had been one of omission rather than commission. The Braves failed to capitalize on the play, and the Bucs won, 3-1.

In defense of Santo, Freese, and Boyer, the rule book should specifically state that a tag is necessary in situations of that type...

Frankie Frisch, while managing the Cardinals in 1934, won a protest concerning the infield fly rule in a game against the Cubs.

The Cubs had the bases loaded with one out when Chuck Klein hit a towering fly in foul ground behind the catcher. The ball was buffeted about in the wind and then proceeded to land in fair territory, about twenty feet from home plate on the first base side. Umpire Bill Klein refused to enforce the infield fly rule, since no Cardinal infielder would have been able to catch the ball with ordinary effort. Klein ran to first base and pitcher Lon Warneke scored on an errant throw to first baseman Rip Collins.

The Cardinals' protest was upheld by League president John A. Heydler, who said, "Klein's fly should automatically have been called an infield fly as soon as the umpire was able to determine it was fair." I think most umpires would disagree with Heydler's decision, although his thinking does protect the runners very well...

I once umpired an American Legion game when a knotty problem developed concerning the infield fly rule. The team at bat had the bases loaded with one out when the batter hit a high fly ball between home plate and first base. I yelled, "Infield fly if fair!" The ball came down in foul territory without any infielder touching the ball. Jt landed on a pebble about three feet from the first base bag and rolled into fair territory. The pitcher picked up the ball and the batter was out, since the ball had trickled into fair territory.

So I guess my scenario of an infielder falling down would most likely be ruled an infield fly.