In December 2013, Holmberg was part of a three-team trade between Arizona, the Cincinnati Reds and the Tampa Bay Rays. The Rays sent a player to be named later (outfielder Todd Glaesmann) and pitcher Justin Choate to Arizona. The D-backs sent pitcher Heath Bell and cash to Tampa Bay. The Reds sent catcher Ryan Hanigan to the Rays.
Holmberg is a stocky 6-foot-3, 225-pound crafty lefty with a very good knowledge and feel for pitching. Some have compared his frame and pitching style to David Wells. Holmberg is more athletic than he looks, and he has toned his body and become much more solid in recent years. He will have to work hard to retain his conditioning and remain in good shape. Strangely, while he does almost everything in his life left-handed, Holmberg bats and plays golf right-handed.
Holmberg has a full repertoire of effective pitches, including a two-seam and four-seam fastball, a changeup, a curveball and a slider. He throws an occasional cutter as well. Holmberg is best known for his command and control of his entire repertoire.
Not overpowering, Holmberg relies upon changing the eye level and the balance of the hitter from among his 88-90 mph fastball, his 82 mph changeup, his 80 mph curveball and his 80 mph slider. Because he can throw strikes with each pitch, he doesn't hesitate to throw any pitch at any count. In his six-year Minor League career to date, Holmberg has yielded a walk rate of less than three per nine innings. Pitching to contact, he has struck out a bit fewer than eight hitters per nine innings. Holmberg takes an average-velocity arsenal to the mound, and he uses it to his advantage by pitching and not throwing.
Holmberg has very "clean" mechanics, with the ability to repeat his polished delivery pitch to pitch. He has the type of command and control that allows him to use the entire plate. Holmberg throws to both corners and up and down to a hitter. His changeup moves very well, dropping quickly and deceiving the hitter. Holmberg works quickly, not wasting time with extraneous movement and nonsense on the mound. He gets the ball and throws it.
Holmberg was among the players added to the Reds' big league club this September. He had fashioned a 2-6 record as a starting pitcher this season pitching for the Reds' Triple-A Louisville club. Holmberg had a 4.66 ERA and a 1.64 WHIP for the International League team prior to his promotion to Cincinnati. He threw 92 2/3 innings, yielding almost 12 hits per nine innings and walking a bit more than three hitters per nine, a bit higher than his usual average.
At this point, Holmberg profiles best as a back-end-of-the-rotation starter. He will have to continue to throw strikes in an effort to go deep in games and eat innings for his club. Holmberg is mainly a fly-ball pitcher, and that could be a bit of a concern in a hitter-friendly park like that in Cincinnati. However, if he consistently gets ahead in counts, he will be able to rely upon his changeup more and induce some swings and misses as well as some ground balls. Holmberg will be dependent upon getting close pitches called his way. Because he isn't overpowering, the team's defense will have to be on their toes, as balls will be put in play.