JD Martinez hits dingers. That’s his calling card, and it might very well get him into an All Star game 17 months after the 2014 version of the Astros said they didn’t want him anymore. It’s a remarkable story and we’ve talked extensively about his offense at New English D and everywhere else. Last year, it was sort of a running joke that lumbering slugger JD Martinez was the Tigers best defensive outfielder, because well, he didn’t have much competition, especially after the Jackson trade.

This year, he has to deal with the styling of Gose in center and the superb Cespedes in left, but he’s doing something kind of interesting on his own, playing a really solid corner outfield. Let’s get the basics covered. In about 700 innings, he’s been +6 DRS and +4.5 UZR. Both of those are excellent marks. Now of course this is relative to other right fielders, so we aren’t stacking him up against the best defenders in the sport, just the best right fielders. Still, a +5 defender over half a season is awesome.

Of course, sample size is an issue with defensive metrics. He was average last year and bad before that. It’s possible this is just a 700 inning fluctuation and in a few months we’ll come to terms with him as an average corner man. We can’t rule that out. But let’s explore the numbers a little bit. Both systems give him small positives for range and sure-handedness, but the real positive has been his arm, rated as +3 runs by both systems. In laymen’s terms, Martinez has prevented three more runs with his arm than the average right fielder. How is he doing it?

If we jump over to Baseball-Reference, we can make use of their held/kill stats. B-R tracks the number of times a ball is hit to an OFer in a given situation (i.e. man on first, single hit) and if the run advances to third, if they stop at second (held), or if they’re thrown out (killed, not the same as assists which cover other tag plays and returning to baes). Let’s see how JD stacks up!

Again, sample size matters. He’s also had slightly more opportunities in some cases, and a lot more when it comes to doubles with men on first than the average fielder, but the key is his ability to hold runners from second on singles. That’s five men Martinez held at third that would have scored on a normal right fielder. Now, we can’t definitely say that he’s had a normal distribution of chances (maybe his have been easier than most), but so far the runs saved value we saw earlier matches the numbers we see here. Martinez doesn’t have a ton of base runner kills relative to the average RF, but he is as good or better at preventing advancements.

Just to give you an idea, holding a runner at third could be worth up to about 0.7 runs given the right situation (i.e. two outs, no other base runners), so these holds can pile up quickly. Of course, with no outs, the hold is much less valuable because of the high probability a runner on third will score at some point. Either way, keeping a runner from taking an extra base is always good, even if it’s not always hugely important.

It’s too early to declare JD a dominating force in the outfield, but so far, everything seems to be lining up in his favor. He’s prevented runners from advancing extra bases, which can have huge benefits to a team that’s struggling to avoid hits in the first place. He’s not going to flash the kind of leather than his fellow outfielders might, but he’s been effective so far this year, and given how much he’s improved the rest of his game, it’s hard to bet against this being a somewhat meaningful improvement.