Drafted in the 21st round of the 2009 draft out of Cowley County Community College (Arkansas City, Kansas), Trevor Rosenthal is a product of the always-excellent Midwest scouting department of the St. Louis Cardinals.
A 6’2”, 190-pound right-hander, Rosenthal spent his age-19 and age-20 seasons pitching for a pair of the Cardinals’ rookie-level affiliates, going a combined 7-1 with a 3.53 ERA, 7.7 H/9, 9.2 K/9 and 2.7 BB/9 in 56 innings. Even though he appeared in 24 games during that span, only six were starts.
In 2011 for Low-A Quad Cities of the Midwest League, Rosenthal blossomed into one of the better steals of the 2009 draft class, as he made 22 starts. Spending the entire season at that level, he finished with a 7-7 record, 4.11 ERA, 9.9 K/9 and 2.3 BB/9. While his command was impressive, he often struggled with catching too much plate at times, resulting in a spiked 8.3 H/9, appearing as more of a thrower than a pitcher.
However, the Cardinals were pleasantly surprised by the right-hander’s success and ability to make adjustments in his first full professional season. They promoted him to Double-A to open the 2012 season.
He responded favorably—to say the least—working as a starter exclusively while posting the best numbers of his career against more advanced hitters. Rosenthal, in his age-22 season, posted an 8-6 record, 2.78 ERA, 6.4 H/9, 7/9 K/9 and 3.5 BB/9 in 94 innings spanning 17 starts.
Looking to improve their bullpen following the All-Star break, the Cardinals promoted Rosenthal directly from Double-A as he made his big-league debut on July 18 at home against the Brewers.
The right-hander’s first stint in the major leagues didn’t go as planned, as he allowed two earned runs on four hits and two walks in four innings, and was subsequently demoted to Triple-A to resume development as a starter.
However, Rosenthal returned as both a more dominant and more confident pitcher when was recalled in mid-August. Appearing in 15 games spanning 18.2 innings, the right-hander registered a 2.41 ERA with 22/5 K/BB down the stretch and held opposing hitters to a paltry .156 batting average.
Apparently the final six weeks of the regular season was just the 22-year-old’s warmup act, as what he has accomplished during the 2012 postseason is absolutely staggering, almost K-Rod-like circa 2002, if you will.
Between the NLDS against the Nationals and NLCS against the Giants, the hard-throwing right-hander has allowed only one hit with 11/1 K/BB in 6.2 innings out of the Cardinals’ bullpen, and he's made some of the game's top hitters look utterly helpless.
As a starter, he works more in the mid- to upper-90s, sacrificing some of the velocity on his fastball for late movement. He still generates exceptional sink while working in the 94-97 mph range, and although he’s rarely flashed it in the major leagues, Rosenthal also throws a hard cutter that has continually improved over the last year. Similarly, he also features an average changeup in his highly impressive arsenal, though it’s an unnecessary pitch for his current role.
Regardless of how un-hittable and dominant Rosenthal has been and continues to be this October, his future is undeniably in the starting rotation. And between he and the team’s perennial top-pitching prospect, Shelby Miller, the Cardinals have a potential duo of legitimate, front-line starters patiently waiting their opportunity.