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Investigating the Struggles of Chris Devenski

Simply put, Chris Devenski has not pitched well in 2019. He’s currently sporting a 4.60 ERA and 4.59 FIP in 31 1/3 innings this season. It is also unfortunately a continuation of his struggles from last season. Do I even dare say it is going back to the second half of 2017? For a pitcher who was considered a key cog in the Astros’ bullpen only two years ago, the decline has been sharp for Devenski.

We’ve witnessed Devenski’s ERA noticeably worsen every season since his major league debut in 2016. In his rookie season with the Astros, we saw the former White Sox farmhand post a 2.16 ERA in 108 1/3 innings. He also finished fourth in the AL Rookie of the Year voting that year. The right-hander then made his first All-Star Game in 2017, which culminated with a 2.68 ERA in 80 2/3 innings and a World Series championship ring. If there were any warning signs with the right-hander in 2017, it was the roughly 10% jump in home run per fly ball rate. Devenski was still a quality reliever, however, in only his second season in the majors. Fast forward to 2018 and we saw more issues begin to emerge. Read the rest of this entry »


The Matt Carpenter U-Turn

Following a 0-for-4 performance against the Twins on May 15th, Matt Carpenter was hitting .140/.286/.272 with a 59 wRC+ over 140 plate appearances. That’s not, um, optimal. One of the Cardinals best players in recent memory was not starting the 2018 season on the right foot. At the time though, Carpenter’s underlying numbers indicated better times were ahead as his .371 xwOBA (expected wOBA) was much higher than his actual .257 wOBA. If you’d sort the largest underperformance difference between xwOBA and wOBA through May 15th for hitters with at least 75 plate appearances, Carpenter’s figure calls out for immediate attention.

Table 1. Underperformance by wOBA-xwOBA through May 15th, 2018 (Min. 75 PA)

Player Name               wOBA            xwOBA          Difference
Randal Grichuk           0.201             0.325                -0.124
Matt Carpenter            0.257             0.371                -0.114
Kole Calhoun               0.174              0.274               -0.100
Avisail Garcia              0.246              0.345               -0.099
Jason Kipnis                0.234              0.330              -0.096
Teoscar Hernandez    0.357              0.447               -0.090
Adam Duvall                0.284             0.371                -0.087
Ryan Zimmerman      0.298              0.384              -0.086
Jason Heyward           0.293              0.377               -0.084
Bryce Harper               0.381              0.463               -0.082

Despite xwOBA not being a “perfect” metric, it still provides a fair amount of insight into a player’s performance. Alas, the metric, to my knowledge, hasn’t accounted for speed data for every player. I am not as well-versed in the Statcast metrics as I would like to be, but that is one missing piece that would be critical in my opinion. At the same time, we can still make reasonable assumptions based on the data at hand.

Carpenter was clearly underperforming based on what one would expect from his batted ball data and historical results. This kind of rough start was surely not going to last an entire season. Eventually, the numbers would start to normalize. But could the shift have played a role in the early lackluster results? Perhaps as he has faced the highest percentage of shifts for a St. Louis hitter in 2018.

Table 2. Shift/Non-Shift Percentage Breakdown – 2018

Shift          Non-Shift
82.4%         17.6%

Look how opposing infields lined up against Carpenter when he stepped into the batter’s box this season. More times than not the infield shifted more towards the first base side, which makes sense against a left-handed hitter.

Screen Shot 2018-08-10 at 12.26.48 PM

Still, indications existed that pointed towards a rebound for the age-32 infielder as his 88.4 MPH average exit velocity through May 15th wasn’t too far off his yearly numbers per Baseball Savant. Starting on May 16th though, the sudden U-turn of Carpenter’s 2018 season took place.

Table 3. Top ML hitters by wRC+ since May 16th (Min. 100 PA)

Player Name               wRC+
Matt Carpenter             203
Mike Trout                     189
Mookie Betts                 188
J.D. Martinez                182
Max Muncy                    172
Jose Ramirez                 170
Paul Goldschmidt         165
Alex Bregman                164
Nelson Cruz                   163
Shin-Soo Choo              161

Holy expletive! Carpenter has been a better hitter, by wRC+, than Mike Trout. That’s something.

Since May 16th, Carpenter has arguably been the best hitter in baseball. His 203 wRC+ leads the majors since mid-May, and his .336/.434/.730 slash line looks darn right impressive. His 32 home runs is a new career-high. Since May 16th, Carpenter has an average exit velocity of 91.5 MPH. Yes, he started to hit the ball harder than he has in years past. In a National League without a clear-cut MVP candidate, I’d think Carpenter will receive plenty of attention. Honestly, he should.

Concerning xwOBA and wOBA, Carpenter went from underperforming to performing closer to what the batted ball data would suggest. In fact, he is now exceeding his expected numbers.

Table 4. xwOBA/wOBA since May 16th

xwOBA      wOBA
.453            .475

Carpenter has also found a way to excel against, or least mitigate, the shift throughout the summer months. For example, his wOBA against the shift was a measly .243 with a .356 xwOBA through May 15th.

Screen Shot 2018-08-10 at 5.15.43 PM

Since May 16th, he has posted a .467 wOBA with a .445 xwOBA against an infield shift.

Screen Shot 2018-08-10 at 5.15.18 PM

If you examine his batted ball data, it is clear that Carpenter has started hitting more fly balls and pulling the ball as the season has progressed.

Table 5. Monthly FB%, Pull%, Cent%, Oppo% – 2018

Monthly       FB%       Pull%       Cent%       Oppo% 
Mar/Apr       44.1%    45.0%       33.3%       21.7%
May               50.8%    47.7%       26.2%       26.2%
June              45.1%     40.9%      36.6%       22.5%
July               49.3%     52.0%      24.0%       24.0%
August          56.0%     64.0%      20.0%       16.0%

Carpenter adjusted to what the defense was giving him. The shift worked for a short while then he essentially shifted where he hit the ball. That’s awfully impressive. In turn, he now has a .401 wOBA against the shift for the entire season. His .320 isolated power would easily be a career-best and has already posted 4.9 wins above replacement with 46 games to go in the regular season for the Cardinals. His results could be a reason to point out why hitters can conquer the shift, yet it remains a difficult task actually to accomplish. Thanks to this adjustment at the plate, Carpenter has made a sudden U-turn into baseball’s best hitter since mid-May.

**Statistics and information as of August 10th, 2018, and courtesy of FanGraphs and Baseball Savant**