Age & Exit Velocity: Making Sense of Matt Carpenter’s Decline

Matt Carpenter has been a great Cardinal. Let’s just get that out there before anything else.

Carpenter’s 29.9 career fWAR is the sixth highest total by a Cardinal in the last thirty years. Ahead of him are two certain Hall of Famers in Pujols and Molina, a should-be Hall of Famer in Edmonds, a coulda-been Hall of Famer in Wainwright, and the eternally underrated Ray Lankford. Carpenter’s Cardinals fWAR is ahead of what Scott Rolen, Matt Holliday and Chris Carpenter produced while wearing the birds on the bat. He’s been a contender for league MVP multiple times. He’s a four time All-Star, a silver slugger winner, and has been to the playoffs in five seasons. Carpenter did all of that while playing three infield positions and not even breaking through as a regular until age 26.

A great career took a sharp turn south when, at age 33, Carpenter struggled through his toughest season as a pro in 2019. He produced a slash line of .226/.334/.392 and just 1.2 WAR in 492 plate appearances. Carpenter’s strikeouts rose alarmingly. His already declining BABIP continued to fall. While it would be nice to explain away his poor season as bad luck, there is little evidence of that.

Carpenter stumbled through a rough first third of the season. As his slump progressed, it seemed to affect his approach at the plate. His K rate began to slide with each passing month. His normally reliable BB rate fell correspondingly.

Injury might have actually done him a favor. On July 16, Carpenter fouled a ball off his foot and landed on the IL. Tommy Edman, already stealing time from Carpenter, stepped in as the starter, and Carp entered an extended rehab assignment where he committed to getting right physically and mentally. When he returned in August, Carpenter managed an improved .328 wOBA. He finally rediscovered himself in September, finishing the season with his best month: .267/.366/.500 with a .364 wOBA.

That’s what happened. The bigger question is why did it happen?

Throughout his career, Carpenter displayed an ability to smash line drives into gaps. That all changed in 2019 when the life simply disappeared from his bat. Carpenter spent most of the season looking like he was swinging underwater. Line drives that would have peppered the wall in previous seasons couldn’t carry past defenders. Fly balls that would have cleared the fence in 2018 became lazy outs.

As the infographic indicates, Carpenter’s exit velocity and hard hit ball % were both well below average in 2019. His xBA was horrendous, and only his walk rate kept his xwOBA from tanking.

The easy explanation for this drop in production is that Carpenter got old fast. There is some evidence to support this claim.

Fangraphs shows a downward trend for Carpenter starting at about age 30 in wOBA, wRC+ and batting average. That trend was interrupted by a stunning resurgence in 2018, where his wRC+ climbed 16 points to 140, buoyed by a career high .266 ISO.

Just considering the flow of these graphs, 2018 looks like an aberration, a blip of brilliance that stands against an otherwise accelerating march toward age-related irrelevance. As great as 2018 was, the downward momentum of the chart picks up again in 2019 in a disturbingly smooth way. If you follow that aging curve to its logical conclusions, shouldn’t the Cardinals expect Carpenter to be EVEN WORSE in 2020? Are the Cardinals doomed to suffer a full season of Carpenter as the worst hitter in baseball? The chart says so! The sky is falling! It is the end of the world as we know it! Everybody hurts. Sometimes.

Well, hold on. That isn’t the way this works. Age is certainly a factor in Carpenter’s decline, but it cannot be viewed as the only factor. Advanced statistics and the club’s own physical assessment of Carpenter paint a slightly different picture.

Carpenter experienced a career worst 87.2 exit velocity in 2019. This ranked 312th among 478 hitters (and some pitchers) included in Baseball Savant’s extensive sample. This corresponds to career lows in barrel % and a massive decline in hard hit ball %. This decline is stunning when placed in comparison to previous seasons. Simply put, when Carpenter made contact in 2017 and 2018, it was very hard contact — top 25 percent in baseball. When he made contact in 2019, it was incredibly weak — in the lower 35 percent of the game.

This precipitous drop in exit velocity is simply too extreme to be explained by an aging curve alone. The data indicates that there is something physical going on here.

The Post-Dispatch (among others) recently reported that the Cardinals noticed Carpenter’s sharp decline in exit velocity and sent him through an intensive battery of tests just after season’s end. These tests measured his strength and physical performance against previously established baselines. The results did not indicate an underlying injury, but suggested that Carpenter had lost muscle mass, weight, and strength.

Their solution? It’s almost elegant in its simplicity: Carpenter was to spend the offseason lifting more weights and eating more food.

For much of 2017-18, Carpenter primarily played first base. He was moved off the hot corner because of persistent back issues and shoulder weakness that sapped his arm strength. When Paul Goldschmidt was acquired last offseason, Carpenter knew he was returning to third. He devoted himself to an offseason regimen tailored around the challenges of his defensive assignment. He stopped aggressive weight training to protect his back and focused on building arm strength and agility.

The result was a solid defensive season. Rarely even an average defender at third, Carpenter provided a neutral DRS (0) and an acceptable -2.1 UZR. His throws seemed crisper and less loopy.

Little did Carpenter know that his efforts to improve his defense were potentially sabotaging his offense. The club believes the lighter, more agile version of Carpenter lacked the core strength to produce a consistently high exit velocity. The result left Carpenter as a line-drive hitter who lacked the strength to consistently power the ball through shifts or into gaps.

As the summer progressed and Carpenter’s weight naturally dropped, the problem was amplified. It’s not surprising, then, that a mid-summer reprieve in AAA, where he could focus on physical recovery and gaining strength, resulted in offensive improvement in August and September.

The Cardinals are convinced that Carpenter’s back can handle increased strength training. More calories should give him a buffer against muscle loss. Better weight maintenance should translate to more consistent power. None of this should take away from his efforts to retain arm strength and agility.

Will their plan work? There are a lot of “shoulds” in that last paragraph, but the club has never wavered publicly in their confidence in Carpenter. They continue to insist that he will be the starting third baseman in 2020. Tommy Edman is Carpenter’s chief rival, and he’s currently slated for a utility role, where he will split time between third, the OF, and shortstop.

Projection systems support this allotment of playing time and do not believe that Carpenter’s decline will continue at the precipitous rate imagined above. Steamer pegs Carpenter for a .237/.352/.441 slash line, with a solid .337 wOBA and 2.1 WAR, which includes a pretty hefty defensive penalty. Edman is projected for a .315 wOBA and a .275/.321/.420 slash, good for 1.2 WAR spread over multiple positions.

Together, the Cardinals believe they have enough depth at third base to avoid considering outside options. Are they right?

The club’s plan is a good one, and there’s reason to trust that Carpenter with execute it with his usual determination. “One of the reasons I’m optimistic, to be honest, is it couldn’t be worse,” Carpenter said to the Post-Dispatch’s Derrick Goold. “I’m an extremely motivated player. Always have been. We have a plan, and I’m motivated as much as ever to right the ship.”