Behind Jason Bay’s fast start

http://cdn.pis.picapp.com/IamProd/PicAppPIS/JavaScript/PisV4.jsJason Bay is currently experiencing the best year of his career so far.
It’s only been 26 games with well over 100 to go, but Bay’s hot start has been invaluable as David Ortiz works out of his devastating slump. On the year so far, Bay’s hitting .321/.482/.619 with six home runs in 112 at-bats through Monday’s game against the Yankees.
Is this sustainable? What is happening with Bay that is allowing him to get off to such a hot start? Should we take what we can get now, or can Bay keep this production up all year? Let’s try to find out.
ON BASE PERCENTAGE
Bay’s walk ratio is the highest it’s ever been, drawing a walk in 23.6 percent of his times at the plate. His career average is 12.9 percent, so there’s a severe change there.
At 30, it’s unlikely Bay has suddenly essentially doubled his walk production, so there has to be something else at work here. And there is.
Out of 483 pitches that have crossed the plate, 259 have been strikes, or 54 percent. Over his career, he’s seen 13,367 pitches and 60 percent have been strikes. That’s a significant change, and I don’t think you can point to pitchers suddenly deciding to pitch around him because he’s been preceded by Kevin Youkilis — if anything, pitchers would want to ensure Youk doesn’t hurt them.
One could contend that pitchers are more willing to pitch to Mike Lowell and those lower in the order than Bay, which could spike his percentages a little, but six percent? No way, not when you consider that for years he was the only true thumper in Pittsburgh and would have been pitched around that much more while in a Pirates uniform.
CONCLUSION: Bay’s on-base percentage will naturally come down as the law of averages rights itself and he starts seeing more strikes.
POWER
We’re going to start our look at power by continuing our discussion of his plate discipline — both historically and this season — for reasons that will soon become relevant.
Bay has only swung at 14.1 percent of pitches outside the strike zone — making contact with 45.7 percent of those — which is again a career best. He generally makes contact with outside pitches a shade over half the time in his career, but he also swings a lot more than the 14.1 percent he is exhibiting this season.
Indeed, while his career is at 19 percent, it was 22 and 21 percent respectively the previous two years. One thought about this rather marked jump in swinging more at outside pitches in 2007 and 2008 could do with not trusting himself to wait for the right pitch given his struggles in 2007 that he started to correct in 2008.
While he’s making less contact with pitches outside the strike zone, he’s mitigating that by swinging at less of them, as any batter would hope to do.
As for swinging inside the strike zone, this is where things get interesting. Bay was always fairly aggressive in swinging inside the zone: prior to 2008 he was in the 65-67 percent range. After his awful 2007, he became far more patient and only swung at 57.9 percent of pitches inside the strike zone, but his contact percentage of those swings remained steady. His swinging in the zone has come up a bit to 61.1 percent this year, but is still significantly below his previous tendencies.
What this means is that Bay became far more selective overall in choosing which pitches to swing at inside the zone. Continuing this train of thought, he is now swinging at a higher percentage of balls in the zone that he can drive.
That would prove evidenced in his current .321 batting average and .619 slugging percentage with a projection to hammer 37 home runs.
He’s had a lot more fly balls on the year than ever before — he’s hitting 47.6 percent of his balls in the air, down from a career 43.7 percent. More striking is that his line drive percentage is the lowest of his career at 14.3 percent. Usually, such a decrease in line drive percentage would prove to be a death knell for a hitter, but it’s working for Bay.
CONCLUSION: Jason Bay’s 2007, by far the worst of his career, clearly caused him to evaluate how he approaches pitchers and made changes that allowed him to rebound in 2008. He’s taken that to an even higher level in 2009 by being more aggressive in the pitches he swings at in the zone (similar to how Kevin Youkilis leapt forward in 2008 as compared to previous years).
His laying off of pitches outside the strike zone is such a significant change, that logic dictates this should trend back to the 20 percent range he’s been at the previous two years.
I contend that it’s possible he stays in this area. In his first full season in the bigs during 2004, he only swung at 16.5 percent of pitches, a percentage that started to consistently rise as he became more and more comfortable in the bigs. 2007 was a rude awakening in how often he chased pitches and he’s trended backwards since.
ALL TOLD…
All told, I’m now of the belief that his on-base percentage is more a product of sample size than any significant change in how Bay approaches things. As for power, I think that Bay’s learned from his struggles in 2007 to tweak his hitting style which has paid dividends. He’s likely to start swinging more at pitches outside the strike zone, which will weaken his overall numbers, but should stay stronger overall than even his 2008 numbers.
Of course, getting his health back after offseason knee surgery before the 2007 season certainly has to be a contributing factor.
Bay ended 2005 with a .306/.402/.559 line in what remains his full career year to date. An approximation of those slash stats from this day out seems to me a more than reasonable projection.