Trevor Rosenthal joine the Cardinals organization in 2009 when he was taken in 21st round. Rosenthal is a Missouri native who played high school ball in Lee’s Summit. He graduated from Cowley County Community College before joining the Cardinals. He pitched exclusively out of the bullpen for the second half of the 2009 season and showed strikeout potential, but also suffered from command issues. In 2010, he pitched at Johnson City for the entirety of the season and started to pick up some spot starts. He hurled 32 innings and ended the year with a 2.25 ERA.
In 2011, Rosenthal pitched at A level as a member of the rotation. He pitched 120 innings in 22 starts and had some pretty good results. His ERA was an unimpressive 4.11, but his peripherals showed that he may have encountered a bit of bad luck. He stuck out 9.95 batters per nine innings and his FIP was a far more respectable 3.04. The Cardinals were impressed enough with his performance to promote him to AA Springfield to start the 2012 season. After 17 very impressive starts that saw him pitch to a 2.79 ERA and 7.98 K/9, he was moved to AAA Memphis. He has thrown three starts for Memphis this season with a career best 12.60 K/9. He earned a spot in the major league bullpen where he remains today.
Rosenthal has appeared in nineteen innings across fifteen relief appearances and has struck out 10.42 batters per nine innings while recording a 3.32 ERA. Rosenthal’s success stems from his very good groundball-incuding tendencies. In addition to striking out more than a quarter of the batters he faces and keeping his walk rate below 10%, Rosenthal has induced groundballs out of more than half the batters he has faced at the major league level. Rosenthal’s stuff isn’t an electric power arsenal, but is tailor-made for a groundball specialist. His best pitch is a sinker that sits in the mid 90s and can reach as high as 98 on the gun. He pairs this pitch with a curve that sits in the low 80s, an 89 mph cutter, and a rarely thrown change-up.
With a four pitch arsenal, Rosenthal has the upside of becoming a good number 3 or 4 starter, but I think his stuff is better suited for a relief role. If he can use his secondary pitches a little more, his sinking fastball could really develop into a fantastic out pitch. Rosenthal has a great shot of making the team next season and will definitely be involved in the battle for the fifth starter spot. Whether he makes the team or not, though, Rosenthal has a great shot of sneaking into the top five on some pundits lists next season.