SF Giants add potential high-leverage reliever to bullpen

The SF Giants were likely going to improve the bullpen at the trade deadline, but unexpectedly did so on Thursday. The team announced that it had agreed to the terms of a one-year, $4.5 million pact with veteran reliever Trevor Rosenthal.

The 40-player roster was full at the time of signing, so the Giants were traded Mauricio Llovera to the 60-day injured list after suffering a flexor strain just before the All-Star break. Rosenthal was added and immediately placed on the 15-day injured list with hamstring strain.

The move will likely give Rosenthal the chance to get his arm back in shape through a rehab mission.

The right-hander was selected in the 21st round of the 2009 draft by the St. Louis Cardinals from Cowley Community College in Arkansas City, Kansas. Rosenthal knows the Giants well as he was on the losing side of the NLCS against them in 2012 and 2014.

Since making his debut in 2012, the 32-year-old reliever has established himself as one of the best relievers of the past decade. During his career, Rosenthal recorded an ERA of 3.36, 2.75 FIP, 1.32 WHIP, 12.1 K/9 and a SO/W ratio of 2.77 with 132 saves.

However, he has been slowed by injuries in recent seasons. The veteran reliever underwent Tommy John surgery at the end of 2017 which knocked him out for the entire 2018 season. He struggled on his return, posting a 13.50 ERA in 15 appearances split between Nations of Washington and the Detroit Tigers.

The eight-year veteran has rebounded well in 2020 where he recorded a 1.90 ERA with 38 strikeouts to just eight walks in 23.2 frames with the Kansas City Royals and San Diego Padres. The Oakland A’s signed Rosenthal to a one-year, $11 million deal in 2021, but he never made an appearance with the team.

As the season began, the right-hander underwent chest outlet surgery after experiencing numbness in his hands and fingers. Rosenthal held a showcase in June of this year, and the Giants must have been impressed with what they saw. When healthy, the former Cardinals reliever throws a fastball in the 90s that he associates with an above-average slider.

That said, the track record of pitchers who fully recover from Tommy John surgery and thoracic outlet surgery isn’t great. There is an element of risk in signing it.

However, the cost was purely financial, so the Giants added a reliever with a good upside midway through the season without giving up prospect capital. If he can regain the efficiency he once had, Rosenthal would immediately become one of the Giants’ best high-leverage relievers.