Red Sox: Drew Pomeranz is allowing home runs at an alarming rate

Boston Red Sox starter Pomeranz is allowing home runs at a career high but has been effective regardless. Is this a stable trend?

Aside from Chris Sale, I don’t think there’s a pitcher in the Red Sox rotation as fascinating as Drew Pomeranz. The former fifth-overall pick has been traded former times and struggled before establishing himself in the Padres rotation last season. But once he had arrived, he was dominant. Which makes it all the more frustrating to see how inconsistent, or consistently bad at times, he’s been since getting traded to Boston.

There’s no point in rehashing last season, so I want to focus on what he’s done this year. In four starts, he’s pitched 21.2 innings with a 4.15 ERA, 1.246 WHIP, and 27 strikeouts. He hasn’t been great, but he’s been effective and that’s definitely worthwhile. More interesting, though, is that he’s been effective despite allowing home runs at a career pace.

The 22 home runs he allowed last season (8 in San Diego and 14 in Boston) set a career high. This season, he’s already allowed five dingers at a rate of 2.1 per nine innings pitched or 5.4%.

Take last night, for example. In the first inning, Pomeranz allowed a home run to Kris Bryant in the that was crushed. This is a Red Sox blog and we’re here to talk about Red Sox players, but his home run just needs to be appreciated for what it was. The 449-foot blast left Bryant’s bat at 106.8 mph and landed on top of the parking garage across the street from the Monster. Yeah, it was huge.

Going back to Pomeranz, it looked like it was shaping up to be a rough night early. Except he settled in and wasn’t great, but was good enough. He would only make one more mistake in the game – a high fastball that cleared the Monster off the bat of Albert Almora. Other than the two home runs, he did his job and provided the effectiveness the Red Sox can only ask for out of a bottom-three starting pitcher.

However, Pomeranz won’t always be so fortunate as to allow home runs without runners on base. Thankfully for Pomeranz, there hasn’t been a runner on for any of the five home runs he’s allowed this season. It’s not necessarily luck since he’s in control of keeping runners off base, but more a case of good timing. Regardless, if he wants to get back to being the pitcher he was in San Diego (if that’s even possible) he’ll have to find a way to manage his rising home run rate.

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This begs one to wonder how sustainable this is, though. He’s allowing nearly one more dinger per nine innings than his previous career high and has seen a two-percent increase in the percentage homers allowed. Is this a sign of things to come? Or just a case of small sample sizes?

Analytically, home runs tend to fluctuate a great amount over small samples but do, for the most part, even out over the course of the season. For this reason, greater emphasis is slowly being placed on Expected Fielding Independent Pitching (xFIP) over the traditional ERA stat and Fielding Independent Pitching (FIP) metric. xFIP holds a pitcher’s homers constant, based on the league average home run-to-fly ball rate.

In Pomeranz’s case, his xFIP of 3.15 suggests that he’s actually been an above average to great pitcher this year, based on talent and outcomes that he is in control of. That’s not to say that the home runs don’t matter, he is responsible for them and they’re certainly important for the outcome of a game, but that over time things should even out. His underlying stats back that up as well.

Opposing batters put the ball in the air 37.2% of the time against Pomeranz last season, of the 92 batters he’s faced this year that number only saw a 0.5% increase. However, his home run-to-fly ball rate is up to 22.7% over 13.6% last year, meaning the five home runs allowed in such a small sample have killed his underlying numbers so far.

That isn’t to say that Pomeranz is due to keep the ball in the yard at an elite rate. Just that his present home run rate is unlikely to continue. Over his career, he’s allowed home runs on just over 12 percent of fly balls hit against him – two percent higher than league average. The reason why xFIP is important in his case is that it suggests that he’s likely to see improvement in the future as his home run rate returns to something similar to his career rate. He’s probably not as good as his 3.15 xFIP suggests, since he allows home runs at a rate above league average, but he’s definitely been better than his 4.15 ERA.

More so, there isn’t anything talent wise that explains why he’s allowed so much this early. Based on PITCHf/x data, his velocity has improved across the board over last season’s, most likely a result of increased strength in his elbow and forearm. His career best 21.7% strike-out-to-walk ratio suggests that his stuff has been more than effective as well.

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The home run rate is alarming at first glance, but the deeper you dig into the numbers, the more it seems like Pomeranz will be alright. There’s no promise that he’ll return to the ERA-leader form he was in during the first half last season, but he’s at least set to see some improvement. If I were to bet on it, I’d be buying his K-BB% and advanced metrics over the home run rate.

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