Kurt Warner and fumbles.

Okay, so when you compare the number of times a quarterback fumbles to the number of times he was actually hit, Kurt Warner is in a class by himself, and not in a good way. The numbers are so high, in fact, that it's hard to imagine that they're simply the result of a player who is on the extreme end of the crappy side of the normal curve when it comes to hanging onto a football.

If you break down Warner's Fumble Rate by Hit (which I defined two posts below, and will call FRH from this point on) by each year he played, it goes:
1999 - 17.31
2000 - 10.53
2001 - 15.15
2002 - 27.59
2003 - 85.71
2004 - 23.08
2005 - 24.32
2006 - 37.04
2007 - 32.43
2008 - 25.00
2009 - 28.89

Wow. Warner had perfectly normal rates of fumbling, and then BAM. In 2002, his FRH jumps from normal, to higher than any other QB's career rate. That in itself isn't surprising; it could just be a high level of variance. But then, Warner never had another season that wasn't higher than everyone else's career standard. It's stark. Is there any possible explanation for why Warner would start fumbling the football more often? As it happens, there is. In 2002, Warner suffered two separate broken hands, one to the base of his hand late in the season, and a multiple fracture to his pinkie in week 4. He'd broken the pinkie once before, in the 2000 season, but the multiple fracture was considered significantly more severe.

It gets better, in fact. Although I realize that I'm descending even further into the land of small sample sizes, if you break down Warner's 2002 season into pre and post pinkie break segments, you find that he fumbled twice in 15 hits before the break... and 6 times in 14 hits afterward. The FRH rates are 13.33% and 42.86% respectively. Once again, that's stark.

So you have a player who exhibits no signs of fumbling much more often than other quarterbacks, who after a broken finger, starts fumbling like nobody has ever fumbled before. Correlation doesn't prove causation, but it sure seems like a pretty solid theory that Warner's week 4 2002 broken hand had an awful lot to do with his struggles to hang onto the football through the rest of his career.