It would have been difficult to root against Tyler Thornburg this spring training. Viewed as Milwaukee’s best prospect in 2012, Thornburg tantalized in his call-up last season. With the big-league club, the 24-year-old split time between the rotation and the bullpen while compiling a sterling 2.03 ERA and a very solid 1.19 WHIP. It is always exciting for fans to see a top prospect make the big leagues, and it appears that Brewers fans will have that opportunity again in 2014. According to Todd Rosiak of the Milwaukee Journal Sentinel, Thornburg and Zach Duke are set to open the season with Milwaukee. The other chief contender for a role, Rob Wooten, was sent to AAA Nashville. Thornburg deserves the roster spot and will help the major league team more immediately than Wooten would have. However, unless Thornburg’s future is in the bullpen, it may have been better for his long-term development to let him break camp in the minor leagues.
Thornburg earned the spot on the major league team. Even before the club’s official announcement, it appeared that Duke, Thornburg, and Wooten would have to compete for the final two spots. Since Duke is left-handed, it is irrelevant to compare his statistics with Wooten or Thornburg. Duke made the team because GM Doug Melvin wanted a third southpaw option behind the untested Will Smith and Wei-Chung Wang. However, since Duke struggled pretty horribly against lefty batters last season (.340 batting average against) it perhaps would have made sense to give spots to both Thornburg and Wooten. Yet even with Duke on the team, Thornburg still deserves to get the final job over Wooten. Wooten was not overly spectacular as a rookie for Milwaukee in 2013, putting up a decent 3.90 ERA. However, his 4.25 xFIP and his incredibly fortuitous 3.7% home run / fly ball ratio indicate that his ERA should have been even higher than it was. Admittedly, the same peripheral statistics indicate that Thornburg’s success last season was also somewhat unsustainable. Thornburg posted an alarming 4.43 xFIP and an infinitesimal 1.4% home run / fly ball ratio, indicating that it will be difficult for him to maintain last season’s level of success.
Still, Thornburg’s raw “stuff,” his pitch arsenal, is simply better than Wooten’s. Wooten’s fastball topped out at 90 MPH last season. As a result, batters swung and missed at his fastball just 4.4% of the time. In contrast, Thornburg’s fastball can reach 96 MPH. Somehow batters whiffed at his heat just 3.8% of the time – less often than against Wooten. However, this oddity is counteracted by the success of Thornburg’s breaking pitches. Opponents batted just .137 against the curveball, compiling an astonishingly weak .307 OPS. Further, batters posted a microscopically small -16 wRC+ against the breaking ball. Thornburg has great command of his curve, and did not allow a single walk with it. Wooten has not had the same level of success with his go-to off-speed pitch, the slider. Batters had very solid results against Wooten’s slider, hitting .284. More worrisome, opponents posted an above-average 116 wRC+ against the pitch. For a pitcher like Wooten that doesn’t have much life on his fastball, the absence of a shut-down off-speed pitch could prove fatal.
However, perhaps it would be better for Thornburg’s long-term future if he begins 2014 with AAA Nashville. Some argue that he is likely to be a reliever for most of his career. If that is the case, then by all means it is right to send him up north with the major league team. Yet consigning this highly touted prospect to a life of toil in the bullpen seems to be a rash decision. His ERA in 2013 as a starter (1.47) was better than it was when he came out of the pen (3.04). While starting this season in the bullpen does not necessarily preclude him from eventually rejoining the rotation, it renders that possibility more remote and more difficult. In the short term, he deserves the job now and can help the team right out of the gate in April. Yet ultimately, it may be better to for him to wait, so that he can prepare for a long-term role in the Brewers’ rotation.