One other thing that bears mentioning...Frank Thomas's BABIP last year was .177 and it's .195 so far this year. While Frank at this point in his career is certainly a unique hitter (he's really swinging for the fences a lot since he can't run) and he's unquestionably a fly ball hitter (gb%'s in the mid 20's) I honestly think he's having a 2 year run of bad luck. In 2004 with a LOWER ld% than in 2005 the Big Hurt put up a .285 BABIP. Yes, his reduced speed is going to have some effect on that but given that he is a fly ball hitter (3-1 fly ball to ground balls) I don't think you can write it all off to him being hobbled by the heel. Just based on his line drives alone he should have been getting about .133 BABIP (and that's assuming EVERY ground ball and fly ball went for an out). His fly balls (which wouldn't depend on speed) account for a large portion of his outs in play and should be falling for hits at a much higher clip than they are.
I plugged his numbers into a formula that I use to predict BABIP. The formula usually undershoots what people should be producing by a bit so if anything the number it spits out would be too low. It expects that even at this year's lower ld% Thomas should be hitting .216 on balls in play. I would expect where he should be to be closer to the .230 range. That's far below the league average but given Frank's heel, his age and his fly ball tendancies I think that sounds about right. If he puts up the power and strikeout numbers he has so far but hits at a .230 clip on balls in play then his batting average so far would be about .256. If I'm undershooting what he can do on balls in play (which is a possibility) that average could creep even higher. Given that the league average on BABIP is around .290-.300 it's certainly possible that Thomas has even more room to rebound in his batting average. But I would expect at least a .256 clip.
As for the power, there's no other way to put it - the power is 100% for real. He's not putting up unreasonably hr/f%'s to get these home runs. He had 15.8% in 2004, 24.6% in 2005 and 17.2% so far this year. While the 24.6% is not reasonable the 15.8% and 17.2% certainly are. Since the league average is 11-12% a guy with 448 career home runs could certainly expect to be in the 16-17% range. Pujols (not the 2006 Pujols either) lives in the 21-22% range to give people a reference point.
The reason Frank Thomas hits so many home runs in limited at bats with a lesser hr/f% is that he hits SO many fly balls. That 3-1 fly ball to ground ball ratio means that he has a lot more chances to hit the ball out. It may not help the batting average but with Frank swinging for the fences you can almost consider him an Adam Dunn lite at this point. He's going to get on base, score some runs and hit a large number of home runs (Thomas in the high-20's/low-30's while Dunn should be in the mid-30's to low-40's)...all the while putting up a bad batting average but in a manageably low number of at bats.