Prompts like this one tend to bring out my more inexperienced side. While I claim to be a Red Sox fan since birth, I only seriously started following baseball this decade, which officially disqualifies me from finding the most underrated Sox player of all time. Special thanks to OOLF for accommodating for this in the prompt.
As you may have guessed by the title, this article is about the most underrated player currently on the Red Sox, rather than of all time. Many have written this player off entirely as the fifth starter or reliever type, which is absurd for a pitcher that just posted 3.0 fWAR in a season.
It's not easy to be a two-pitch guy in the Show. Some days, everything's clicking. Your curveball looks like Kershaw's, and the fastball is doing everything possible to disrupt the batter's adjustment to that curve. You're untouchable. The next day, that curve won't stop spinning out of the zone, leaving a fastball that no longer fools anybody and an emergency changeup that wasn't a major league pitch in the first place. Sound familiar? The guy I'm talking about is Rich Hill.
One year ago, that definition could have been used for both Drew Pomeranz and Rich Hill, but the concept no longer holds up, because Drew Pomeranz is no longer a two-pitch guy. He now boasts a three pitch repertoire with a powerful knucklecurve, a four-seamer that sets the curve up, and a cutter that was good enough to be used roughly 13% of the time per Fangraphs' Pitch Type.
Drew Pomeranz has changed his identity as a pitcher fundamentally, and there are consequences to this change in identity. Fangraphs already went over many of these consequences here, and I'll be expanding on what that means for Pomeranz going forward.
First and foremost, what Pomeranz did in San Diego is now the most accurate portrayal of his ability that we can glean anything from. From 2011-2015, Pomeranz was a different pitcher in a dozen different ways, from his swingman role, to Coors Field, to his complete change in repertoire. Pomeranz isn't that pitcher anymore, and it is ridiculous to think he will be that again when he has a solid contingency that actively prevents that scenario. A third pitch is a new variable that calls for a change in equation, which makes his previous results worth little more than an indication of health problems (which is a valid concern).
As for his stint with the Red Sox, where do you begin? The elbow problems, his blowing through his three year innings average by more than 60 innings, our famous Fenway pressure on new acquisitions, take your pick. The data is tainted with the Red Sox, but it's clean in San Diego. None of those problems surface in a major way in his time spent there.
So now we're left with a relatively small sample size and a redefined pitcher. That's not an ideal situation, but it is better than where we were before. FIP adjusts Pomeranz's ERA for BABIP to a 3.15 mark, which was the 11th best mark among starters in the first half, good for a 77 FIP-. He's moving to the AL East, so let's take the more pessimistic view that xFIP takes, a 3.61 mark that was 25th among starters. That's about the level of performance I'm expecting from Pomeranz next year.
A healthy season from Drew is by no means a certainty, with his recurring elbow problem flying in to ruin the day at every turn, but it would look something like this: Jake Arrieta compiled 3.8 fWAR last season with similar peripherals in just under 200 innings. If Pomeranz can manage 170 innings again and maintains the higher K rate, we're looking at a similar total in a full season, which is arguably ace quality.
Therefore, as a famous gun-jumper, I present to you Drew Pomeranz: Fourth Ace in the Red Sox Rotation. Overrate him as you will.