Detroit Tigers outfielder J.D. Martinez is really good. In 2014 he hit .315/.358/.553, wRC+ of 152, with a 3.9 fWAR in 129 games. In 2015 he's hitting .287/.349/.555, wRC+146, with a 4.6 fWAR.
If you've paid any attention to baseball at all over the last two years, his production over the last two campaigns is hardly a newsflash. Yet Martinez was not considered a hot prospect in college and he's exceeded the expectations of scouts to a great extent.
Martinez was a very successful player at Nova Southeastern University in Florida, hitting .428/.530/.770 in 2009, with 41 walks against 26 strikeouts in 187 at-bats. Although the NSU Sharks play good competition in the Sunshine State Conference, it is still a Division II school. Despite his performance, his level of competition and an unorthodox swing ensured that Martinez was lost in the shuffle on draft day, falling to the 20th round where he was selected by the Houston Astros.
Note that it was the old front office under Ed Wade that drafted Martinez, not the current sabermetric-oriented regime under Jeff Luhnow.
Martinez adapted quickly to pro ball, hitting .326/.380/.540 for Tri-City in the New York-Penn League after signing, winning the league batting title. Still, a college senior tearing up the NY-P is not unusual, so he still had things to prove.
I did have a report from a trusted source that his physical tools were under-rated. Here's what I wrote on him in my 2010 book:
He was a monster in college, and he was a monster in pro ball, too, dominating the Appalachian and New York-Penn Leagues in his pro debut, posting a +39 percent OPS at the latter stop and winning the league batting title. Martinez didn’t get a lot of pre-draft buzz, but his physical tools are rated as at least average by some scouts. Obviously pro ball wasn’t much of a challenge for him, and he looks to have legitimate hitting skills. Although we need to see how he responds to higher levels (his plate discipline needs some work), I think the Astros have a potential sleeper here. Grade C but should be tracked closely.
Martinez eased doubts that the numbers were fluky by hitting .362/.433/.598 with 15 homers in 88 games for Low-A Lexington, then .302/.357/.407 in 50 games after a leap to Double-A, skipping High-A entirely. There were fewer complaints about his swing and it looked fine to me when I saw him play in the Texas League, though I'm hardly an expert on swing mechanics. The comment entering 2011:
Martinez proved last year that his talents were real, destroying the South Atlantic League (+49 OPS) and holding his own after moving up to the Texas League (+7) without an intervening stop in High-A. The scouting reports are positive: he has a good swing and can drive the ball, and his physical tools are solid. About the only physical negative is mediocre running speed, but he is a decent athlete overall. I know he went to a smaller college, but still, a lot of people underrated this guy. I think he’s legit. Grade B-.
That was the last time he appeared in the book. Martinez split 2011 between Double-A (.338/.414/.546) and the majors (.274/.319/.423), exhausting his rookie eligibility.
As you know, after the solid start Martinez scuffled for two years in Houston, hitting .241/.311/.375 in 2012 and .250/.272/.378 in 2013. Injuries were an issue and the complaints about his swing popped up again. The Astros eventually cut him, he signed with the Tigers as a free agent, then suddenly turned into one of the best hitters in the American League.
What happened? Eno Sarris at Fangraphs broke this down back in June, discussing how Martinez studied other successful hitters then altered his swing to add more upper-cut. Quoting Martinez himself:
"I used to always think, ‘Hit down on the baseball.’ But then I realized that’s not what everyone else is doing.
"When I got hurt in 2013, I was watching Jason Castro. He changed his swing plane, and that’s when I noticed him doing it and I was like, Whoa. What’s this guy doing differently? When I started watching it and asking questions, I got intrigued by it. Then I was injured, so I just went to my computer and started looking up everybody’s swing.
"At first I thought maybe it was just Castro. Then I went into the weight room, and that was when Ryan Braun was going through the PED scandal. They were showing all of Ryan Braun‘s swings on ESPN over and over. And then it just hit me: there it is again. I went back to the video after the game, and stayed an hour after the game, just looking everyone’s swings up on video. Miguel Cabrera, Albert Pujols, Braun, Allen Craig, all these guys."
Whatever he's done, it is certainly working.
This is a fascinating story. Even with his old unorthodox "hit down" swing, Martinez was an extremely productive hitter in college and in the minors and was solid when he first got to the majors in 2011. Big league pitchers made adjustments however, and for awhile it looked like original scout doubts about his swing were prescient.
But then Martinez adjusted back and so far the pitchers have yet to find a counter-measure to his new approach. He showed a willingness to learn and change, a reminder that adaptability is a key strength in the Darwinian exercise of major league baseball.