On April 11th, the 24-year-old was called on to pitch against Seattle Mariners ace Felix Hernandez in his first start of the season and just the third of his career in place of the injured Matt Harrison. The young right-hander kept Texas close over 4.0 innings pitched, allowing a pair of runs with two strikeouts and holding the Mariners 0-for-6 with runners in scoring position as the Rangers went on to defeat Seattle, 4-3, at Safeco Field. Grimm scattered five hits in the no-decision. On April 21st, the Bristol, Tennessee native again encountered the Mariners, this time allowing two runs (one earned) on six hits with a careerhigh nine strikeouts to lead Texas to an 11-3 victory over Seattle at Rangers Ballpark in Arlington to complete a three-game sweep - their first series sweep since June 18-20, 2012 in San Diego. Grimm stayed aggressive throughout his 6.0 innings, holding Seattle to one hit in 11 at-bats with runners in scoring position. In Justin's next start against the Minnesota Twins on April 26th, Texas' fifth round pick in the 2010 First-Year Player Draft hurled a career-best 7.0 shutout innings to help the Rangers to a 4-3 win at Target Field. The University of Georgia product scattered five hits, struck out four and did not issue any free passes in the 94-pitch appearance.
Others receiving votes included Grimm's Rangers teammate Nick Tepesch (2-1, 2.53 ERA, 21.1 IP, 14 SO, 3 BB); Brandon Barnes (.375, 15 H, 3 2B, 1 HR, 5 RBI, .468 OBP) of the Houston Astros; Conor Gillaspie (.311, 19 H, 3 2B, 1 3B, 2 HR, 4 RBI) of the Chicago White Sox; and Dane De La Rosa (1-0, 2.70 ERA, 13.1 IP, 12 SO) of the Los Angeles Angels of Anaheim.
In recognition of his American League Rookie of the Month Award, Justin Grimm will receive a specially designed trophy, suitably engraved, for his accomplishment.