Villarreal's potential, however, is only that if he can't stay on the mound. That's why the Tigers are taking such caution with him after his second bout of elbow soreness since the summer.
The Tigers cleared the hard-throwing 25-year-old right-hander to pitch winter ball in his native Venezuela with the idea of getting him about 15 innings, enough to work on some things with his delivery and get a head start on next spring while still allowing him an offseason of rest.
Vilarreal joined the Caribes de Anzoategui in early December and pitched in three games, hurling three scoreless innings and allowing one hit with a run and a strikeout. He complained about some arm problems in mid-December and was sent back to the U.S. to have his elbow examined by team doctors, according to the Venezuelan newspaper El Universal. The tests revealed inflammation, but no structural damage.
The Tigers confirmed Villarreal was examined with nothing serious revealed. Though Villarreal was reportedly expected to be sidelined until Jan. 2, the Tigers and Villarreal agreed to shut him down for the rest of the winter and have him focus on being ready for Spring Training, rather than have him return cold for the Venezuelan League playoffs.
Villarreal was also diagnosed with elbow inflammation in August. He returned to action after six days and picked up where he left off in his torrid summer with some very good outings, but struggled through September. When the Tigers made out their postseason roster, they left Villarreal off the seven-man bullpen in favor of lefty Drew Smyly and sinkerballer Rick Porcello, both starters for most of the season.
Despite that decision, it's difficult to overestimate how important Villarreal could be to Detroit's 2013 bullpen, especially if the club keeps its relief corps as is without another move. His fastball averaged 97.1 mph last season, according to fangraphs.com, and he honed with his slider into an effective second pitch despite throwing the slider less often.
Villarreal allowed 16 earned runs on 38 hits over 54 2/3 innings, good for a 2.63 ERA and a .201 batting average. His 66 strikeouts ranked second among Tigers relievers behind only Joaquin Benoit.
On a team that didn't have a consistent lefty reliever, Villarreal held left-handed hitters to a .190 batting average (12-for-63, 19 walks, 18 strikeouts).
If the Tigers stick with their bullpen as is, adding only top relief prospect Bruce Rondon, Villarreal has a chance to play a major role in middle relief, potentially even getting some setup work if Benoit or lefty Phil Coke get closing opportunities. That's a big reason why the Tigers have been deliberate in his offseason work, and why Detroit isn't taking any chances with him now after his second elbow flareup.