This is why the Red Sox signed J.D. Martinez

The Red Sox are good at, well, everything right now. There honestly isn’t an area of the game that has been a cause for concern since the first week of the season, as the baserunning and bullpen have both stabilized since they played at home for the first time. The offense has also come on in a big way since that homestand began, and their overall numbers don’t look anything like the team that was struggling to score when the season first kicked off. Amazingly enough, they have been the best offense in the game by just about any measure. The Red Sox lead all of baseball in wRC+, runs scored, Isolated Power, On-Base Percentage and fWAR, among other categories. The best part of this lineup, of course, is that there are different players contributing on different nights and Alex Cora’s vision of a battle to start every game is working to a T. That said, there is one player who seems to be directing this offense. It’s not Mookie Betts, Hanley Ramirez, Rafael Devers or Xander Bogaerts, though all of those guys have obviously been amazing. Instead, it’s J.D. Martinez, who has somewhat quietly been the guy everyone was expecting and is showing why the Red Sox were ultimately willing to go right up against the top-tier luxury tax threshold to bring him into the fold.

Jayne Kamin-Oncea-USA TODAY Sports

Obviously there hasn’t really been a point in the season in which the Red Sox haven’t looked good, but I’m sure you’ll recall the same can’t be said for the offense. While the team was still winning in the very early going, they were doing so in close, low-scoring games that were carried by the pitching. It was too early to worry and ultimately turned out to be just a one-week cold stretch, but Martinez was the most notable guy to be struggling. The lineup as a whole hadn’t really clicked at that point, but it seemed like the free agent signing was the key guy who was struggling day in and day out. That quickly changed, and as soon as he started hitting consistently the offense turned into a juggernaut. At this point in the year, those early-season struggles have been completely erased and Martinez is looking awfully familiar.

Through Thursday’s action — this is being written before Friday’s game, so if he comes in as a pinch hitter and goes like 0-8 in a 27-inning game, I apologize — the slugger is up to 74 plate appearances on the season and he’s hitting .338/.365/.618 for a 161 wRC+ that puts him 61 percent better than the league-average hitter. A lot of players put up eye-popping stats early in the year, of course, but what makes this particularly scary for opponents is that it looks pretty damn sustainable.

For one thing, that wRC+ is actually worse than the mark he posted in 2016 after he went absolutely bananas with Arizona in the second half (and played pretty damn well with Detroit before that, too). The power is the most notable part of Martinez’ game, and it’s showing up in a big way of late. Overall, he has a .279 Isolated Power, which would seem unsustainable for mere mortals but is to be expected for Martinez. He is, after all, coming off a year in which he posted a .387 ISO (!). He’s doing everything you’d expect from a power hitter — most simplistically he’s hitting the ball in the air and hitting it hard. He has a 65 percent hard-hit rate, per Fangraphs! In fact, Fangraphs has four projection systems on their player pages (ZiPS, Steamer, Depth Charts and THE BAT), and all but one project Martinez to have a higher ISO the rest of the way than his current .279 mark. That seems like a cheat code.

The other part of this high quality contact is that Martinez is having a ton of success on balls in play. With his ability to square up the ball so often, the slugger generally carries high batting averages on balls in play. That is continuing this year, though it’s to an unsustainable extreme with a .422 mark. That will come down, but that should correspond with an increase in walk rate. Martinez is currently walking in just five percent of his plate appearances, and he’s coming off a career-high 11 percent rate. Even if he doesn’t get back to those heights, the projection systems see him running a rate around nine percent for the rest of the year, which is a significant boost. All told, the increase in walk rate should at least come close to cancelling out that BABIP regression, meaning the Martinez we’re seeing now could and arguably should be the Martinez we see for the rest of the year.

Mookie Betts is justifiably getting all of the attention right now — he’s amazing — and Hanley Ramirez has been the most fun story (in this writer’s opinion) but Martinez is the best hitter on this team. That is what the Red Sox signed him to do, and while we will be dealing with some subpar defense more often than we’d like, we’re seeing why they were willing to promise him some time out there to make sure he’d come aboard. This lineup is seeing the positive regression we were expecting from so many returning players, but the addition of Martinez has brought this unit to another level, and the great performance they’ve gotten from him to start this year shouldn’t change too much going forward.