Mariners News: Introducing C.J. Riefenhauser


The Mariners and Tampa Bay Rays agreed to a six-player deal on Thursday night that saw Logan Morrison, Brad Miller and Danny Farquhar head to Tampa in exchange for Nate Karns, Boog Powell and C.J. Riefenhauser. We have previously written about the additions of Karns and Powell, and tonight we will discuss Riefenhauser.

Originally a 20th round selection by the Rays in 2010, Reifenhauser spent just over four seasons in the minor leagues before getting the call to big leagues in 2014. As a rookie, the southpaw reliever appeared in 7 games and posted an 8.44 ERA. Riefenhauser struck out 2 and walked 3 across 5.1 innings of work.

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Reifenhauser split the 2015 season between the Rays and their triple-A affiliate in Durham. He struggled once again in the show, going 1-0 and registering a 5.52 ERA through 29 appearances. The Yonkers, NY product fanned 7 and issued 7 free passes across 14.2 innings of work.

The 25-year-old’s big league numbers are pedestrian at best, but he has fared remarkably well over the past three seasons in Durham. Riefenhauser sports a record of 9-6 with a 2.15 ERA through 85 appearances. He has struck out 109 and walked 40 across 113.0 career innings in triple-A. His 2.73 strikeout to walk ratio is impressive, as is the fact he has held the opposition to just 1.062 walks/hits per inning.

Through six seasons in the minor leagues, Riefenhauser is 30-23 with a 2.77 ERA. He began his career as a starting pitcher, but made the permanent transition to the bullpen during the 2013 season. The move proved to be a good idea, as Riefenhauser has been much more productive working out of the ‘pen.

Riefenhauser utilizes a three pitch arsenal. The Chipola College alum’s out pitch is his slider, particularly against left-handed hitters. His fastball registers in the high 80’s, and he relies heavily on it early in counts. Riefenhauser’s changeup is another plus pitch, but he rarely throws it.

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The Mariners are hoping C.J. Riefenhauser will develop into a shutdown lefty specialist. That is certainly possible, but he has struggled in these situations thus far in his career. Left-handed hitters posted a .370 batting average against Riefenhauser in 2015. Worse yet, lefty’s clubbed three homers off him in 27 at bats last season. Admittedly, the sample size is small, but those numbers are obviously less than ideal.

The prognosticators are anticipating Riefenhauser to show significant improvement next season. Baseball Reference projects the young southpaw to go 2-2 and post a 4.36 ERA through 33 innings. FanGraphs is predicting he will finish 2-2 with a 4.12 ERA across 40 appearances. If he can keep his ERA south of 5, Riefenhauser could be a very useful asset in the Mariners’ bullpen next season.

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It’s unlikely C.J. Riefenhauser will ever represent the Mariners at an All-Star Game, but the chances of him developing into a serviceable reliever are pretty good. He has plenty of team control left, and he still has minor league options remaining if he needs more seasoning. Adding Riefenhauser makes the M’s ‘pen more versatile, and could spell the end to Joe Beimel‘s tenure in Seattle. Look for Riefenhauser to compete for a job next spring in Peoria.