I had started to write a piece like this myself, but I'll cede the space to Tokarz after he was an optimist for like the first time ever. - Kurt
Thought experiment: If I told you three months ago that Austin Jackson would be the best player (by WAR) on the Tigers and, in essence, as valuable to Detroit as Matt Kemp is to the Dodgers, how would you have reacted? My guess is that I would have been laughed off the site.
And yet here we are, in May, and both of those things are true. Jackson is worth 1.3 more WAR than second-place Andy Dirks and third-place Miguel Cabrera. He's also worth just 0.1 WAR less than Matt Kemp, which pretty much makes the difference between them a wash. Statistically, as of May 16th, Austin Jackson is the third best center-fielder in baseball and the fourth best position player (behind Josh Hamilton, David Wright and Matt Kemp).
Of course, there's little doubt in my mind that Jackson will regress a little bit. Not only are we dealing with small sample sizes, but Jackson has a BABIP of .378, and that's probably unsustainable. His HR/FB rate of 10.6% is also a career high, and I could see a bit of regression there. But the question shouldn't be "Is Austin Jackson going to regress?" but rather "How awesome is Austin Jackson?" The answer is clear: pretty darn awesome.
While we don't have much data from 2012, we have enough to draw a few conclusions. Eric Seidman, a writer at Fangraphs, wrote an article in 2009 that examined how quickly it took certain statistics to stabilize. Some (like contact rate) stabilize relatively quickly, while others (like Isolated Power) take much, much longer to stabilize. So far, we can draw conclusions on the following statistics: swinging percentage (how often players swing at given pitches), contact rate, strikeout rate, line drive rate and pitches seen per plate appearance.
Therefore, if we want to analyze Austin Jackson's progress as of now, we should examine these statistics. Below, I have compared Jackson's performance in the 151 plate appearances he has this year to his 2011 and 2010 seasons.
Line Drive Rate:
These numbers show us that Jackson's plate discipline has improved dramatically. He's cut his strikeout rate dramatically, partially due to a lower swinging percentage (and a lower swinging strike percentage as well). His contact rates are very close to his breakout 2010 season, and he's hitting a boatload of liners. This leads me to conclude that Austin Jackson has fixed at least some of his plate discipline woes, and so he will hit for a higher average (probably around .280). It looks like fixing the leg kick has helped quite a bit.
What about the walk rate, a career high of 12.6? Well, Seidman indicates that we can't draw any conclusions based on this rate until Jackson reaches 200 plate appearances. That said, we can project some possible conclusions with the use of a little bit of math (the rhetorician in me is really hoping these calculations are correct).
Let's start by assuming that Jackson doesn't walk for the next 49 plate appearances that it'll take for us to get stability in that walk rate. His walk rate would be 9.5%, which would still be a full point above last year (the best walk rate of his career). If Jackson walks in 7% of those 49 plate appearances (that's his lowest career rate), his walk rate would stabilize at 11%. At worst, I project Jackson's walk rate will hover around 9%, meaning that he'll provide value in terms of on-base percentage as well as batting average.
I'll stop with the numbers here; power is incredibly hard to analyze and takes forever to stabilize, so I'll save it for better men than myself. But the fact remains: the best defensive center fielder in baseball just improved his performance at the plate so much that he is rated the third best center fielder based on WAR (and fourth-best player) in baseball. Even assuming regression and the risk that comes with breakout performances, I can think of three center fielders I'd rather have: Josh Hamilton, Matt Kemp and Andrew McCutchen. Austin Jackson is really, really good at baseball. And hopefully this post has helped explain how good he's become.