Examining a Trevor Rosenthal – Boston Red Sox Pairing
Yes, it’s another article about the Boston Red Sox bullpen. Despite ranking in the top 10 in ERA, FIP, and WAR, the Red Sox need to find another arm for their bullpen. The unit leads the American League with 15 blown saves and reliable relievers like Matt Barnes and Marcus Walden are being pushed to their limits. The Washington Nationals recently released right-handed pitcher Trevor Rosenthal, and some peg him as a fit with the Red Sox. Rosenthal was awful with the Nationals, but is he worth the risk for the Red Sox?
Should Boston Red Sox Pursue Trevor Rosenthal?
To say Trevor Rosenthal has struggled in 2019 is like saying it’s cold at the north pole. Rosenthal was a disaster with the Nationals, recorded a 22.74 ERA, 10.12 FIP, and a 12.26 xFIP in 6.1 innings. Rosenthal made 12 appearances on the season, so it’s not like this is the biggest sample. That said, it’s impossible to look past numbers this rough.
To make matters worse, Rosenthal missed all of 2018 while recovering from an elbow injury. Now 29 years old, Rosenthal is approaching the age where pitchers tend to fall off a cliff in terms of production. There’s a very real chance that Rosenthal doesn’t have anything left in his tank and no longer deserves a spot on the major league roster.
However, he’s worth the risk for the Red Sox. Prior to his elbow injury, Rosenthal was a solid reliever for the St. Louis Cardinals. Rosenthal made his major league debut back in 2012 and posted a 2.99 ERA and a 2.60 FIP over 325 innings in St. Louis. He was a strikeout machine, posting a 12.0 K/9 over that six-year sample. While he walked more batters than you’d like (4.0 BB/9), all the other numbers made him one of the better relievers in baseball at his peak.
Perhaps what’s most enticing about Rosenthal is his history as a closer. Boston simply hasn’t found anyone capable of replacing Craig Kimbrel and the Red Sox are losing games because of it. From 2014 to 2015, Rosenthal recorded a combined 93 saves for the Cardinals. While he’ll probably never reach that level again, he clearly has the mentality and the necessary makeup to pitch in the ninth inning.
So What Went Wrong?
Rosenthal was a good pitcher as recently as 2017, but what caused him to fall off a cliff? In short: everything. Rosenthal can no longer strike out batters at an elite rate, as his 7.11 K/9 is significantly lower than the 12.0 K/9 he posted with the Cardinals. Additionally, Rosenthal’s BB/9 is an atrocious 21.32, which is obviously atrocious.
On the bright side, his contact splits aren’t dramatically different from past years. In 2017, Rosenthal induced ground balls at a 40.8% clip while getting fly balls at a 31.1% rate. In 2019, Rosenthal posted a 35.0% ground ball rate and a 35.0% fly ball rate. These numbers, while worse, aren’t significantly different than what he was doing two seasons ago. Additionally, he’s allowing hard contact on 25% of his at-bats as compared to 26.0% in 2017.
In other encouraging news, Rosenthal hasn’t lost anything on his fastball. According to Fangraphs, Rosenthal’s 2019 average fastball velocity was 98.0 miles-per-hour. This is actually an improvement from his 97.4 career fastball velocity. Additionally, his cutter and changeup velocity align with his career norms.
What the Red Sox Can Do
Based on the measurable data, Rosenthal’s biggest problem appears to be consistently finding the strike zone. The righty still has an impressive heater and a decent set of complementary pitches, but he just can’t locate them to save his life. Coming back from an elbow injury at 29 years old is never easy, but the fact he still has his velocity implies that he could return to form if given enough time.
The best move for the Red Sox is to sign Rosenthal to a minor league deal with the Pawtucket Red Sox. The Nationals are still on the hook for his $7 million dollar salary, so Boston won’t need to worry about a bidding war breaking out. If he can finding the strike zone with any regularity, the Red Sox can add him to the 40-man roster and get a key bullpen arm for basically nothing. If he can’t, then there’s no harm done. Regardless of Rosenthal’s success, the Red Sox should still try to find another reliever before the trade deadline.