What Numbers J.D. Martinez Looks At

I was recently talking to J.D. Martinez about launch angle and exit velocity and the like. Besides helping me to update my language, he also told me he didn’t really track his performance by those measures. Same thing for some other metrics I mentioned. It’s clear Martinez has some substantive thoughts on hitting, though. It would be strange if he didn’t use any of the data available to him. So I asked him… what do you track? What numbers do you look at?

“I track my swings and misses in the zone,” he said. “I can deal with swing and miss out of the zone. If I’m swinging and missing in the zone, I don’t like that. That tells me something is wrong. It tells me that something is not right with my swing, I’m fouling balls off. If the ball’s in the strike zone, I should be able to hit it. There are certain situations, take a pitch, that’s fine. But when I swing and it’s a strike — especially on a fastball and I’m not hitting it — that’s not good.”

The good news is that Martinez has generally improved upon this portion of his game since developing into more of a fly-ball-hitting slugger in his first year with the Tigers:

This graph seems to reveal an unambiguously positive trend. It’s also a tiny bit misleading, though. See that last data point on the graph? That’s Martinez’s zone-contact rate with the Tigers this year. And only the Tigers. Of course, Martinez doesn’t play for them anymore; he’s employed by the D-backs now. And even though he’s hit 25 homers with his new team, his strikeout rate has soared to 28.9% — and the reason, in part, is a big reversal in his zone-contact rate.

It’s weird that we have a guy who’s killing the ball in ways that are easy to see while also maybe struggling when it comes to the underlying mechanics.

Is he being pitched differently? Maybe.

He’s gone from seeing 36.6% breaking balls to 30.2%. That may make some sense: he’s hitting sliders better than he ever has before (by pitch type values) and he’s also seeing more sliders than he ever has before. “The furthest balls I’ve ever hit are breaking balls,” Martinez told me. “They go the furthest, they have the spin on them already.”

He’s noticed that they weren’t throwing him many fastballs before. “I’ve gone a full game and maybe seen one fastball? Several times it’s happened,” he said. “You just have to recognize and swing at a strike. I don’t care what it is; if it’s a strike, I have a chance to hit it.”

The pitches that have most replaced the breaking balls are four-seamers and cutters. Let’s see where those cutters are being thrown now as opposed to earlier in the season.

With the Tigers:

With the D-backs:

They’re throwing the cutter further down. They’re also throwing more high and away four-seamers, but that can’t be a problem for Martinez. He’s the 14th-best four-seam fastball hitter in the last three years.

But those cutters low and away in the strike zone? They’re leading to a drop in zone-contact percentage.

J.D. Martinez is killing it. But pitchers are throwing him a pitch that’s possibly a problem for him. Of course, if he’s still a top-40 hitter against the cutter. And if he’s tracking his zone-contact rate, he’s probably spotted this potential trouble area. He’s probably ready for the next cutter low and away.

With a phone full of pictures of pitchers' fingers, strange beers, and his two toddler sons, Eno Sarris can be found at the ballpark or a brewery most days. Read him here, writing about the A's or Giants at The Athletic, or about beer at October. Follow him on Twitter @enosarris if you can handle the sandwiches and inanity.

newest oldest most voted

Hypothesis: When hitters change leagues midseason they will experience an uptick in swinging strikes in the zone (and possibly declines in other plate discipline metrics).

Theory: When hitters change teams, and particularly when they change leagues so that they’re not in any of the parks they’re used to playing in. They experience an adjustment period where they need to adjust to subtly different park factors such as lighting in the park, glare, different kinds of cloud covers, etc.

Has anyone looked at this question? Maybe what’s happening to Martinez is systematic to most players.


I always felt that was why Justin Upton struggled so much during his first 4.5 months as a Tiger. He needed time to get used to being in the AL after spending his entire career to to that point in the NL.

The Real McNulty
The Real McNulty

Upton specifically mentioned he could see the ball very well in San Diego, I believe