The Boston Red Sox rotation has shown some chinks in the armor lately. Was the early season success a mirage? Is this latest perceived swoon representative? We’ll use some advanced metrics to dig in.
It seems like ages since the Boston Red Sox rotation looked to be among the best in baseball. Rick Porcello has shown his warts… again. Drew Pomeranz looks like his arm might fall off. David Price has struggled with some minor health issues. And even Chris Sale has been scuffling lately. So where do they stand after a bit more than a third of the season? Let’s take a look!
There are a number metrics we will use to examine the staff here, and none of them are the traditional wins or ERA. The reason for that is that we want to get at how good they are, not how good their results are. ERA depends heavily on defense and some luck.
Wins require the offense scoring runs. Neither is something that digs into how well a pitcher has performed all that well. A terrible defense will allow more balls in play to poke through the infield or fall into the gaps. A team with a terrible lineup might saddle its starter with losses on nights when they go 7 IP allowing just two runs. So what are we going to use?
Time to go to fWAR.
Overall, the staff ranks 5th in fWAR. I like fWAR more than rWAR for pitchers because it isn’t based on runs allowed. It’s based on FIP. The concept behind FIP is to strip away contextual noise as much as possible, leaving you with as clean a look you can get at what a pitcher directly controls. That means strikeouts, walks, and home runs for the most part. So we’ll use that here.
The club has amassed six fWAR to date, putting them behind the Indians (6.1), Phillies (6.7), Nationals (7.6) and Astros (9.5). Putting aside just how bonkers that 9.5 fWAR from the Astros is, the Red Sox rotation certainly looks good enough.
The Yankees, their closest division rival, have 4.7 fWAR. The next closest are the Rays with 3.5, good for 13th in baseball. If the goal this season is to win the division and avoid the play-in game, the rotation is doing its part in getting them there. At least by this metric…
Speaking of FIP.
Fielding Independent Pitching is a method of focusing on what a pitcher can control. Essentially, it looks at the three true outcomes and ignores balls in play. While the three true outcomes aren’t truly 100% in the pitcher’s control, they are the things a pitcher can control most. Variables like catcher framing, weather, park dimensions, and umpire accuracy can all impact these events. But for the most part, FIP is better at predicting future success than ERA. That doesn’t mean it’s a full replacement, however. One of the best ways to use FIP is to compare it to ERA and then try to explain the difference.
Where do the Red Sox starters rank in FIP? They drop down one spot to 6th, with a 3.59. How does that compare to their ERA? It’s a bit better. Their ERA of 3.79 ranks 9th in baseball, so perhaps there is a reason to expect a bit of improvement as we move forward. The Astros lead baseball in both metrics, by the way.