I haven't written a post in awhile, but I am now home for the summer and will hopefully be writing a few posts a week. I wanted to write one today on Jose Bautista. I wrote about him at the end of last season here, and I wanted to do a study on why he is even better than last year.
The major difference between this year's version of Bautista and last year's is his much better batting average. He is still managing to hit a ton of home runs, but after hitting only .260 last season, he is now hitting .353 (all statistics through Saturday's games), good enough for second in the AL. One of the biggest reasons behind this increase in batting average is that his BABIP (batting average on balls in play) has increased from .233 to .321 this year. His career rate of .273 suggests that he was somewhat unlucky last year, and has gotten lucky this year. This may be misleading, as his changed swing naturally leads to more fly balls, usually meaning a lower BABIP. It seems as though last year he was simply trying to hit the ball out of the park, while this year he has become more of a line drive hitter while still hitting home runs. This can be seen in his line drive %, which was only 14.4% last year and is up to 17.1% this year. Line drive % shows how "lucky" a hitter is getting, as line drives are usually end up falling for hits, while ground balls and fly balls are more frequently outs. The increase in LD% shows that Bautista hasn't actually been any luckier this season, he is simply hitting the ball much harder in a higher percentage of at-bats and is being rewarded with a higher BABIP and subsequently batting average.
We can demonstrate what could have happened in previous seasons had Bautista hit as many line drives, leading to a higher BABIP. BABIP is calculated as: (hits - home runs) divided by (at-bats minus strikeouts and home runs plus sac flies). Last year, Bautista had 569 at-bats, 148 hits of which 54 were home runs, 116 strikeouts, and 4 sac flies. If we set his hits total as unknown, we can solve for the amount of hits he would have had with different BABIP. He had a total of 94 non-HR hits last year, and if he had even had his career BABIP of .273, he would have produced 110 non-HR hits. This would have left him with a batting average of (164/569) = .288. If he had this year's .321 BABIP, he would have had an batting average of .322, much closer to this year's .353. The difference in batting average from his career to this season is due to both luck and skill, and unfortunately we can't exactly differentiate the two, but we do know that Bautista has become a better hitter, and is hitting for a higher average at least due to some skill.
So where is the other 30 point difference coming from? The BABIP formula shows us that it comes from the number of home runs and strikeouts a hitter accumulates (also sac flies, but they are minimal and can be ignored). As discussed in the last post, a large determinant of the number of home runs a hitter has is his HR/FB ratio, which is mainly due to luck. Obviously, hitters like Bautista who make a conscious effort to hit fly balls very hard will have higher HR/FB rates, and thus more home runs. The league average is usually around 10.6% (actually, the HR/FB rate is now below 9% for 2011), and last year Bautista ended the year with a 21.7% rate, more than double league average. This year, Bautista has a 31.3% HR/FB rate, which is insane. This means that roughly for every three fly balls he hits, one ends up over the wall for a home run. This is by far the highest rate in the majors this year, with Lance Berkman having the second highest rate at 23.4%, which is 34% lower than Bautista's rate. Even with Bautista's violent swing, this rate is bound to regress at least somewhat towards the mean. This shows that Bautista has gotten somewhat lucky this year, but it is impossible to determine what his final HR/FB rate will be, so we cannot determine exactly how lucky.
The last determinant of BABIP is from strikeouts. Bautista has dramatically increased in this area, decreasing his strikeout rate from 20.4% last year to 17.3% this year. This may not sound like much, but over a full season of 500 or so at-bats, that's 16 more balls put in play, and with a BABIP of .321, five more hits. That's about 10 extra points on his batting average over a full season, simply due to striking out less. What makes this even more impressive is that while he is striking out less, mainly due to the fact that he decreased his swinging strike percentage from 7.7% to 6.7%, he still has the ability to hit the ball extremely hard, actually harder this year. In almost every case, a hitter will sacrifice power in order to make more contact, yet Bautista has managed to become better at both. This is certainly not luck, and we can attribute this part of his increased batting average all to skill.
What does this all mean? I have presented a lot of different statistics, and what I hoped to accomplish was to show that while Bautista has gotten a little lucky in his huge increase in AVG this year, it has mainly been from skill. Although at first you may want to credit luck from his increased BABIP, he hasn't simply had more balls "find holes" this year, he has been hitting more line drives, which show that he has become a better hitter. Yes, his home run total has been somewhat inflated by his incredible HR/FB rate, so maybe we shouldn't expect him to hit 40+ home runs the rest of the season and instead expect him to finish with 50 or so home runs. If his HR/FB rate regresses even all the way to last year (which I don't expect it will), he should still end up with 48 home runs. Finally, he has managed to swing and miss less pitches, which decreases strikeouts and allows him to hit more balls in play. This is due to a systematic adjustment, and is not lucky at all. Although we know Bautista won't end the year hitting .350, with all of these factors we just discussed, we can reasonably expect him to finish the year hitting .320 or so. Many people expected Bautista to slump this year and not be able to hit as well as last year, but he has managed to play even better, and should end up with better numbers this season than last, which is hard to believe.
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