Red Sox Prediction: Is Drew Pomeranz a Henry Owens or a Jon Lester?

Drew Pomeranz has yet to define who he is in a Boston Red Sox uniform. Is he more akin to ace Jon Lester or bust Henry Owens?

Despite a strong start to his 2017 campaign, Drew Pomeranz has had a bumpy road since the Boston Red Sox acquired him in a trade last July. Coming over from the San Diego Padres in exchange for heralded 19-year old flamethrower Anderson Espinoza, his mid-season 2.47 ERA and 10.1 K/9 set expectations high.

However, a 4.59 ERA with the Red Sox to close out the season before getting exiled to the bullpen for the playoffs cast a looming cloud over Pomeranz’ future in Boston. Would he be moved in the offseason? Kicked out of the rotation for good?

A trade of Clay Buchholz and an arm injury to David Price answered those questions effectively, and Pomeranz started 2017 as the number five starter in the rotation following a lingering arm injury. And he started off well, firing six strong innings of one-run ball against the Baltimore Orioles.

The arm injury may be temporarily in the past, but the questions surrounding Pomeranz continue to linger. We know who he was in other uniforms; a failed starter in Colorado, an effective reliever and spot starter in Oakland and a borderline ace in San Diego. But who is Drew Pomeranz in Boston and what can he become?

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To answer that question, we’ll define our parameters based on historical example. Looking back at the recent history of lefty starters in Boston, we’ll use one as an example of a ceiling and one of a floor: Jon Lester and Henry Owens (I’ll let you figure out which one is which).

Let’s start by examining the qualities of the pitches themselves: velocity and spin rate. Neither of these metrics is necessarily indicative of a good pitcher, although there’s undoubtedly a correlation between the two.

According to Baseball Prospectus, Pomeranz’s fastball averaged 91.88 mph last season, good for 156^th out of 228 pitchers who threw at least 100 pitches. By comparison, Lester averaged 93.05 mph and Owens averaged 89.73 mph. Pomeranz is dead in the middle between the two, usually unable to blow hitters away like Lester but not utterly relying on off-speed offerings like Owens.

According to The Sabermagician, the spin rate of Pomeranz’ curveball from 2015 was 1,325 revolutions per minute (rpm), ranking 48^th in the league. For reference, pitchers like Corey Kluber, Craig Kimbrel, Sonny Gray and Rick Porcello all had their curveballs clocked in above 1,400 rpm. Interestingly, Lester and Owens are bunched together at 1,047 rpm and 1,039 rpm, respectively.

Pomeranz actually features a tighter curve than Lester or Owens, and the results have correlated as such. He has allowed a .220 opponent average on his curveball over his career, featuring a 32.8 percent strikeout rate and just a 3.2 percent walk rate.

But even more important than the nature of the ball once it’s released is what happens to the ball once it leaves the bat. Here are some numbers from 2016:

Lester: 20.2 percent line drives, 46.9 percent ground balls, 32.8 percent fly balls, 0.122 home-run-to-fly-ball ratio, 1.43 ground-ball-to-fly-ball ratio

Pomeranz: 18.4 percent line drives, 44.2 percent ground balls, 37.4 percent fly balls, 0.197 home-run-to-fly-ball ratio, 1.18 ground-ball-to-fly-ball ratio

Owens: 20.3 percent line drives, 30.5 percent ground balls, 49.2 percent fly balls, 0.172 home-run-to-fly-ball ratio, 0.62 ground-ball-to-fly-ball ratio

There are some conclusions to be drawn here. The first number that pops out was Pomeranz’ absurdly high home-run-to-fly-ball ratio. He’s always been a pitcher who likes to get the ball in the air, a strategy that has treated him well in the spacious confines of Oakland Coliseum and Petco Park. In home-run-susceptible stadiums like Coors Field and Fenway Park, however, those tendencies have gotten him into trouble.

When the ball isn’t hanging in the air, however, Pomeranz finds much more success. He allows relatively few line drives and despite his fly ball tendencies, he gets balls on the ground far more than the extreme fly-ball pitcher in Owens.

It comes down to fastball location. These heat maps show where in the zone that the trio of pitchers threw their fastballs in 2016 (for Pomeranz, the data begins when he was dealt midseason to Boston).

Notice the sheer amount of red in Pomeranz’ middle and upper part of the strike zone, and compare that to Lester’s ocean of blue. The combination of Pomeranz’ lackluster velocity and power-inducing location has and will continue to allow big damage. This is what separates the game’s best pitchers, like Lester, from the rest of the pack: optimal stuff and location.

Overall, Pomeranz shows a middle ground to the extremes that are Jon Lester and Henry Owens. He doesn’t possess the elite corner-grabbing accuracy of Lester and shows the fly ball and home run tendencies of Owens, but he also doesn’t show a complete lack of velocity and he is able to limit hard contact on the ground.

Next: Red Sox: What’s wrong with knuckleball pitcher Steven Wright?

If Owens is a 1 and Lester is a 10 in terms of Boston lefties, then expect Pomeranz to be a 5: a serviceable back-end starter who can rack up the strikeouts but is constantly haunted by the long ball.