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Is Matt Carpenter Improving?

Sort of! A little bit!

MLB: Milwaukee Brewers at St. Louis Cardinals Jeff Curry-USA TODAY Sports

It’s been quite a stretch for the Cardinals. They’ve strung together 15 wins in 19 games, and won 29 of 44 since the All-Star break. There are positive signs galore since August 9th. For instance, they’ve gained six games in the standings on both the Cubs and Brewers. They have the second best FIP in the game since then. Seven regulars plus the rejuvenated Harrison Bader have at least a 100 wRC+ in that time frame, and six of those are over 120. There’s an all-time Cardinal great who doesn’t quite fit either of those groups, but he’s showing signs of life. He’s the one we’re going to talk about today. Matt Carpenter is improving, but is he back?

You know the story by now about Carpenter’s 2019 season. He got off to a slow start, rebounded for a month, and then injuries sidetracked him. He strained his lower back around June 29th and went on the IL, hurried back to action on July 12th, fouled a bunch of pitches off of his foot, and went right back on the IL with a foot contusion after just a few games.

He came back from the second injury just in time for the dreadful California swing. He stumbled through the first few games. Then, he slowly started to heal. Since those first two games back, he’s hitting .240/.391/.400, good for a 115 wRC+. We’re dealing in small samples to be sure. It’s 20 games and 65 plate appearances.

Here’s how his season looks chunked out in 19 game segments, via FanGraphs (through Tuesday’s game). I’ve added gray demarcation lines for the months, a red demarcation line for his 19-game rolling wRC+ of 119, and an ice blue chunk for anything below an 80 wRC+. Note that this is through Tuesday- the pinch hit appearance Wednesday made his wRC+ slip from 119 to 115.

Other than a blip in late May and a few weeks in June, he hasn’t reached the 119 wRC+ line at all this year before right now. It’s hard not to notice that a lot of his time below 80 is sandwiched around his back and foot injuries. He didn’t hit the IL until July 2nd, but he had fallen out of the starting lineup as early as June 26th because of a flu that had him using an IV. In other words, the flu and the back injury covers at least that last week of June, and the foot caused issues in July into early August. A lot of his under-80 wRC+ games occurred when he was fighting or healing from injuries, but I digress. The bigger story here is that he has shown improved results over the last few weeks, and his improved health is even a logical reason for it.

Now comes the hard part. Is he really back, or is this a magic trick? I’m going to complicate matters by divvying his season up into quarters. Warning- here, thar be small samples, so take all of this with a giant grain of salt:

  • The beginning of the season through May 11th (40 games)
  • May 12th through June 17th (29 games)
  • June 18th through August 5th (15 games)
  • August 6th through August 27th (19 games)

Let’s start with an easy gauge- his plate discipline. In addition to the four quarters of his 2019, I’m also listing his 2017-2018 average.

Matt Carpenter, 2019 Plate Discipline

Timeframe BB% K% BB/K O-Swing% Z-Swing% Z-Contact% SwStr%
Timeframe BB% K% BB/K O-Swing% Z-Swing% Z-Contact% SwStr%
3/27-5/11 14.3% 24.0% 0.60 20.1% 65.8% 86.0% 8.8%
5/12-6/17 12.2% 24.3% 0.50 22.5% 62.4% 84.6% 8.2%
6/18-8/5 8.1% 33.9% 0.24 25.8% 64.3% 84.3% 9.0%
8/6-8/27 17.2% 26.6% 0.65 21.3% 60.0% 79.4% 9.5%
2017-2018 16.2% 21.8% 0.74 18.9% 56.2% 87.7% 7.2%

His late June through early August stretch is certainly an outlier here, with fewer walks, many more strikeouts, and a spike in chase rate. The most current stretch is also a bit of an outlier, with higher rates for walks, strikeouts, swinging strikes, and lower contact on pitches in the zone. Some of that last part is alleviated by the fact that he’s swinging less both inside and outside the strike zone. Clearly, he’s taking a more patient approach and earning more walks. It’s a bit of a mixed bag, though. The contact rate on pitches in the zone is a huge red flag, particularly because it’s significantly worse than every other section of this season and even more extreme compared to 2017-2018.

Now let’s take a look at his quality of contact:

Matt Carpenter, 2019 Contact Quality

Timeframe ISO Optimal % wOBACON xwOBACON
Timeframe ISO Optimal % wOBACON xwOBACON
3/27-5/11 0.134 18.52% 0.311 0.363
5/12-6/17 0.235 15.49% 0.440 0.383
6/18-8/5 0.055 11.43% 0.230 0.402
8/6-8/27 0.163 11.76% 0.408 0.355
2017-2018 0.239 12.80% 0.416 0.449
Optimal %: Batted balls between 22 and 38° launch angle, 95 mph EV or more, per batted ball event

That’s more confusing. He’s seen a noticeable bump in his ISO, but his xwWOBA on contact is as bad as it’s been all year. None of his four quarters this year come close to his expected wOBA on contact baseline from 2017 to 2018, but two of his four wOBA on contact quarters this year are right in line with that baseline. Put another way, he’s getting similar results both in his current stretch and his May to June stretch to what he got in 2017-2018, but it’s a result of outperforming his batted ball quality this year and underperforming it in 2017-2018. For all of the noise in these four sections, his xwOBACON seems reasonably steady across the groups, meaning a lot of the variance comes down to just noise and batted ball luck. More importantly, all four sections are significantly lower than 2017-2018, most notably his current hot stretch.

His percent of batted ball events at optimal velocity and angles have been steady going back to mid-June. He’s not hitting the ball optimally with any more frequency during his current hot streak than he did during his mid-summer cold streak. On the other hand, his percent of optimal contact since June really isn’t that far out of line with what he did from 2017 to 2018 when he was a much more productive hitter. There’s a lesson in there I’ll get to shortly.

We have one more table to review:

Matt Carpenter, 2019 Batted Ball Types

Timeframe LD% GB/FB Pull Center Oppo
Timeframe LD% GB/FB Pull Center Oppo
3/27-5/11 25.5% 0.49 45.4% 31.5% 23.2%
5/12-6/17 22.9% 0.80 45.1% 25.4% 29.6%
6/18-8/5 20.6% 0.93 37.1% 31.4% 31.4%
8/6-8/27 27.3% 1.40 50.0% 32.4% 17.7%
2017-2018 24.6% 0.55 47.8% 30.3% 21.9%

It looks like there was a conscious effort made to go the other way earlier in the year, from mid-May through early August. There’s been an effort in his recent stretch to pull the ball more, a reversion of sorts to his 2017-2018 approach. If you average it all out and compare simply all of 2019 to his 2017-2018 baseline, his line drive percentage is down only marginally (24.6% before to 24.3% this year) while his opposite field percentage has spiked to 25.4% this season from 21.9% before. His line drive percentage in the current stretch is certainly encouraging.

I’ve buried the lede, though. There’s a set of numbers in that graph that cry out. His number of groundballs have increased exponentially throughout the year to the point that his GB/FB in the recent stretch is two and half times as large as it was in 2017-2018. It started the year below 2017-2018, then kept increasing to the point that he looks like a massively different hitter. If you want to know why his xwOBA on contact is down, even with comparable optimal contact percentages, that’s why. He’s hitting too many groundballs.


It would be an overstatement to suggest that Matt Carpenter is back to his previous levels. There are some little nuggets of hope in this data, but there’s a lot more work left. More line drives and a better approach at the plate are great starting points. That he’s chasing less frequently is another good sign.

On the other hand, the slipping contact in the strike zone is scary, as is the groundball rate. There have also been, seemingly, several different approaches this season, like a hitter desperately trying to adjust and find equilibrium. That’s likely why he had such a long rehab stint before returning the second time- an attempt to get his swing and approach where it works best. Getting more of his contact into the optimal range as he had earlier in the season and his GB/FB back to 2017-2018 levels would be a significant step. If he starts doing that, you’ll know he’s truly back.