BP: Can C.J. Wilson keep it up?

After a successful experiment in the spring that ended with entrance into the rotation, former reliever C.J. Wilson has rattled off four straight quality starts to begin 2010. His continued success would go a long ways towards ensuring the Rangers stick at or near the top of the American League West, so the question is whether or not that is possible. After all, relievers usually end up as relievers because they're not good enough to start.

Wilson always had a deep repertoire for a reliever, with a four-seam fastball that could hit 95, a change-up and a slider. As a starter, he's dropped the four-seamer in favor of a two-seamer with movement that tails away from right-handers, moving between 89 and 92 mph. He uses all of these pitches low and inside to hitters, focusing on picking up ground balls off the end of bats and forcing opponents to pop up the ball off the lower half of their bats. So far, he's been successful. Wilson has a 1.15 ground ball/fly ball ratio, and has yet to allow a home run.

This tactic was on display last night against the White Sox, as Wilson allowed two runs over six innings in a 4-2 Rangers win. He induced three straight grounders to third to begin the game, working low in the zone and forcing White Sox hitters to swing at pitches they couldn't do anything with. Wilson showed a great understanding of how to pitch contextually, which is impressive for a reliever who, even with the deep pool of pitches to pull from, relied heavily on his fastball and its velocity in the past.

Just 59 of Wilson's 104 pitches were strikes, but, in the same vein as his last two starts he was able to pick up enough ground ball outs (11) that it didn't matter. He previously had 13 ground ball outs against the Red Sox and 10 versus the Yankees. The Rangers infield defense is solid enough that they can contribute to Wilson's success, and he strikes out enough hitters (five last night, 7.4 per nine on the season) that he can get himself out of a jam as well.

There were plenty of reasons to doubt that Wilson could succeed as a reliever, such as stamina and ability to retire right-handed hitters. Thus far he's making Texas look smart.

Marc Normandin is an author of Baseball Prospectus.