Trying to figure out Matt Carpenter, the hitter

In each of the last three seasons, Matt Carpenter has been a similar, yet fundamentally different type of hitter. In 2013, Carpenter, overall, was one of the best hitters in baseball (high average, very high on-base percentage, and above-average power). Last year, Carpenter remained a high OBP guy, but saw both his average and power dip. So far this season, his average is down to its lowest level in the last three seasons (largely because of a two-month slump after a bout with extreme fatigue), but his OBP is team's highest yet again and his increase in power has been significant (leading the team in SLG, ISO, HR). Also of note, and I don't intend to be alarming, but he appears to be in a funk to close out the month of August as well: recording four hits in his last 35 at bats (.114 BA, .238 OBP).

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On the surface, Carpenter's overall approach to hitting seems pretty much the same as he remains near the very top of the National League in terms of pitches seen per plate appearance. At his current rate, Carpenter will have seen 24 fewer pitches this season than last (multiplied over 600 plate appearances), which is a pretty insignificant difference. Thus, while Matt Holliday pleaded for more aggressiveness from Carpenter back in spring training, it does not appear that much has changed on that front:

Yet, has Carpenter been more or less successful against certain pitches this season compared to years prior? Let's take a closer look.

Versus Pitches 95+ MPH

Carpenter's batting average has fallen off a cliff on pitches 95 MPH and above, as he has recorded only three hits in 32 at bats. The lone bright spot is the fact that of the hits he has notched, they have been relatively powerful (a home run against Milwaukee, a home run against Cincinnati, and a single against Cincinnati), producing a .188 ISO. For a hitter that usually sprays 95+ MPH pitches all over the diamond, his performance in 2015 has been particularly troubling. Now, if he is sacrificing performance against 95+ MPH pitches for success elsewhere, it is perfectly reasonable, so let's dig a little deeper.

Versus Breaking Balls (Curve, Slider, Knuckle-Curve)

Nope, he is not doing very well against breaking balls, either. He's had slight improvement from last season, especially regarding isolated power, but there is a still a significant drop-off from 2013. Moving on.

Versus Fastballs (FA, SI, FC) 87 to 93 MPH

Here we go; now, we're talking. For those who are fans of batting average, as you can see, Carpenter is in the same ballpark (.290 to .310) as 2013 and 2014. And for those who prefer a little more substance, his isolated power against 87 to 93 MPH fastballs is the highest it has been in his career. Thus, while he may be struggling against pitches 95+ MPH, he is doing just fine against fastballs that align more consistently with the league average. The fact is, a league average fastball is roughly 92 MPH, so it is a good thing that Carpenter is showing no signs of struggle against this type of pitch.

Versus Changeups

This is where it starts to get fun. Sure, a .250 batting average isn't necessarily headline worthy, but take a look at his ISO. Six of his 10 hits have gone for extra bases: home run #1 (off Yordano Ventura), #2 (off David Price), and #3 (off Chris Rusin), as well as three doubles. Again, this makes me wonder if Carpenter is knowingly sacrificing success against faster pitches to time up changeups for more powerful success.

First Pitch Success

I was curious to see if Carpenter was swinging at the first pitch more frequently this season. The table above shows that it does not appear that he is. While we have seen an increase in power in nearly every other situation, it is not the case here, as he has a 2014 Jon Jay-like ISO on first pitches this season.

Reaching a Full Count

For perspective, in 2015, per Baseball-Reference, hitters have reached a full count in 12.4% of plate appearances (12.6% in 2014 and 12.8% in 2013), which means Carpenter is 59% above league average for this category this season. What is important to note is Carpenter is significantly outpacing his full count performance from the last two seasons, particularly in terms of isolated power, and his numbers are vastly better than the league average slash of .207/.442/.340 as well. Can part of this success be attributed to luck? Absolutely, but I'll be honest, when Carpenter reaches a full count, especially this season, I really do like the Cardinals' chances.

Home Runs

As you can see, Carpenter is not missing on mistake pitches, with the majority of his 19 home runs coming on pitches middle to middle-in.

Bottom Line

Don't get me wrong Carpenter is still a very good hitter (and he is a major component of the Cardinals offense), but he has been uncharacteristically streaky in 2015. While I do not know for sure, I personally think it is a combination of dealing with extreme fatigue (and whatever the underlying condition is for that symptom) and the strike zones of home plate umpires (as 14.1% of should-be balls have been called "strikes"). If you have any theories regarding Carpenter's hitting performance, please include them below.

Credit to BaseballSavant.com for its incredibly in-depth PitchF/x search function.