I thought I would put together some charts to illustrate Javier Baez's progression throughout the minors.
Shown are strikeouts (red) and walks (blue) as a fraction of cumulative plate appearances. Separate trend lines indicate changes in seasons or levels. I have omitted the first couple of data points in each series for the purposes of prettification.
Baez's strikeout and walk rates have to be viewed through the lens of his prodigious power. He's obviously going for broke, and thus some strikeouts are to be expected. It would be helpful if he could limit them to the 25% range, as he was able to do in Peoria and Daytona. Likewise, It would be nice to see walks in the 11-12% range, as pitchers avoid his comfort zone, but at least the trends are promising.
As Cub fans, we are all intimately familiar with theories of player development for prospects with (ahem…) questionable plate approaches. Of these, one that is often repeated is what I think of as the "Forced Exposure Theory," which holds that for a prospect who is hitting really well in spite of his approach, the correct move is to promote him to a higher level. At the more advanced level, the player will no longer be able to dominate and as a result will be driven to make adjustments to his approach. This hasn't really happened with Baez, who has abused Southern League pitching. Fortunately, his walk rate has improved somewhat anyways.
And about that power (as measured by isolated slugging percentage)….
It's simply been ridiculous this year, and throughout his career, really.
One thing I noticed in going through Baez's game logs is that he has yet to be hit by a pitch in AA. Getting hit has been a pretty valuable part of his game thus far, he was hit 12 times in 2012 and 11 times in the FSL this year. The lack of HBP's in Tennessee is something to keep an eye on, as it could be part of a change in approach, a different level of pitching, or just a fluke. Players like Chase Utley and Carlos Quentin have added a lot of career value by taking pitches for the team, and it could be an asset to Baez, particularly if his walk rate remains low.