What to Expect From J.D. Martinez’s Power in Fenway

Several days ago the Boston Red Sox aquired J.D. Martinez, presumably under the expectation of adding a lot of power to the lineup. Since 2015, he’s eighth in home runs with 105, a league-best .284 ISO (four thousandths of a point ahead of Nolan Arenado), and his 147 wRC+ puts him at sixth in all of Major League Baseball.

Yes, he can hit for average as well but I’m not interested in that. What I’m curious about is whether or not the famed Green Monster in Fenway Park will be a hindrance to Martinez’s power.

He’ll now be playing 82 games each season in Fenway Park, where every time he comes to bat he’ll have the Green Monster in peripheral view; a 37.2 foot high wall 310 feet down the left field line and as far away as 380 feet at left center. There are dozens of hits every year at Fenway that could have ended up as home runs in other parks, but instead are eaten up by the Green Monster and spit back out as (extra) base hits.

To attempt to approximate the minimum required launch angle and exit velocity to hit a home run over the Monster, I needed visual proof. Using Baseball Savant, I searched all the home runs hit in Fenway Park during the Statcast era.

I keyed in on home runs specifically hit to left/left center field, spanning the entire range of that monstrosity. Using the spray chart tool, I found any and all homers that were as close to the barrier of the GM (Green Monster) as possible. I came across one that seemed to fit perfectly and cleared the wall just enough.

That’s Steven Souza, Jr. driving a home run under (nearly) perfect metrics to breach the wall.

Just to be certain that this was as close as I could get, I wanted to know what the weather conditions were that day. I was able to find the barometric pressure and how mother nature’s influence could have affected this hit, in terms of exit velocity. Air pressure matters because when its low, baseballs go further due to less friction on the baseball and vice versa.

  • Game time: 1:35 PM
  • Game Duration: 4 hours and 32 minutes
  • Approximate time HR was hit 5:00PM
  • Conditions at time of HR: 50 degrees, light rain, wind blowing NW at roughly 16 MPH with gusts up to 27 MPH
  • Game barometric pressure: A consistent 29 inches

OK, so what jumps out at you? Wind speed, right? All Fenway Park’s contact to left (center) head in a northerly direction. The low barometric pressure and wind speeds gives me two possible caveats for this examination.

However, as you see in the GIF, the trajectory was fairly high and it cleared the wall by a couple of feet. It’s impossible to tell if the wind was blowing (and how hard) during Souza’s homer, so keep those things in mind since they are variables that don’t make this investigation exact when applying it to Martinez.

Souza’s hit metrics on that homer were as follows:

  • Breaking ball at 80 MPH
  • 93 MPH exit velocity
  • 33.5 degree launch angle
  • Hit distance of 344 feet

We can use those measurements to get a guesstimate of what Martinez could or would have done hitting regularly in Boston. I produced the following spray chart using his last three seasons under the backdrop of Fenway Park.

J.D.  Martinez(2)

Clearly he’s able to hit to all fields; you could suggest that a fair amount of his hard contact is concentrated in the area of the GM and that’s what I’m going to hone in on. Yet with the height of the wall, some of those home runs (hit in other ballparks) could have been inhibited.

I inspected all Martinez’s home runs since 2015, shifted focus to the launch angle and exit velocity using the Souza home run as my model, and ran a query of all his contact using the metrics it would take to clear the wall.

I set the minimum launch angle to 30 degrees, to give a little breathing room, because it appears as though Souza’s homer cleared the wall by a foot or two; I did the same for exit velocity, starting it at 90 MPH. For minimum hit projection range, I used the shortest distance to the GM; 310 feet.

Breaking it down even furter, I ensured that homers hit to left center had ample room and momentum to clear the wall; e.g. the 310 foot distance wouldn’t work for a ball he actually hit to left center, for example.

All together, Martinez had a total of 121 batted ball events under the conditions of my launch angle/exit velocity/distance figures. 24 of those 121 BBEs resulted in contact to left field; 11 would have ended up being GM-clearing home runs if hit in Fenway, but instead were recorded as outs.

So, taking events strictly within the region of left to left center field in Fenway, Martinez could be expected to hit about 43% more home runs facing the GM over the next three years of his contract.

Remember, that doesn’t include contact to other parts of the field. If you look back to the spray chart, you’ll see several spots marked home runs that would fall short in Fenway.

Furthermore, using his home run total from 2015-2017, we could reasonably surmise that he’ll hit an average of about 35 home runs for the next couple of years. Adding in these 11 outs as home runs, Martinez will be expected to hit roughly 9% more home runs (3 per season) at Fenway, so long as he is a Red Sox.

So, the monster won’t be as problematic as I originally assumed upon hearing of this acquisition for Boston; it might actually improve Martinez’s power.

7 replies »

  1. As a Yankee fan, I’m hoping he tries to alter his swing to account for the Green Monster and ends up throwing off his mechanics. I’m not looking forward to faxing him 19 times a year for at least the next 2-3 seasons. He was the thumper in the middle of the lineup they truly missed since Big Papi retired.


  2. What’s the first thing that jumps out at me? It’s effing RAINING! You’re worried about barometric pressure because “heavy air” “weighs” on the ball, but you disregard much heavier water, falling from the sky? UM..

    The rest of the work isn’t bad, but the baseline metric is rough, at best. You simply look to see the launch angle/velocity needed to clear the Monster (use physics, don’t forget to calculate height from the ground at which the ball is hit – knee-high balls must be hit at higher angles, chest-high pitches can be more on a line, due to being almost 3 feet higher to start) or, if you want real data, you should have averaged the numbers for the wall-scrapers that left the past few years. That, at least, would have adjusted out the variance presented by wind/rain/pressure and given you a baseline for what type of ball generally just barely leaves Fenway in LF. Why you chose to pick one random HR that just cleared and use it as a guide, especially when it was hit on a bad weather day, is beyond me.


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