Sam Deduno is so close to becoming a regular major league starter he can taste it. So can the Minnesota Twins, who desperately need Deduno -- or Cole De Vries, or Esmerling Vasquez, or P.J. Walters -- to take the final step. Minnesota has only one pitcher locked into the 2013 rotation, rookie Scott Diamond, who became the ace of the 2012 staff with an 11-8 record and 3.69 ERA after being recalled in May. After that, who knows? Deduno, who made his first major league start this season at age 29, has been the best of the rest. He's 6-4 with a 3.84 ERA in 13 starts, but the Twins are still unsure whether he can make the final leap. In a 5-3 loss to the Chicago White Sox on Saturday, he walked five batters and threw two wild pitches in four innings, raising more red flags. The walks raised his total to 48 in 13 starts over 75 innings since he was added to the 40-man roster on July 8. "I think it was just a bad game," Deduno said. The Twins are inclined to agree. One, Deduno had been very good in his previous three starts, going 2-1 with a 1.80 ERA and only six walks in 20 innings. Two, Deduno is an exciting pitcher with a live arm that, if under control, could be valuable. The Twins have looked at the numbers; they know a pitcher who walks 1.5 batters every inning cannot succeed in the major leagues. But if Deduno can get that figured out, he'll not only be a major league pitcher, he'll be a successful one. His curveball is a plus pitch that he can throw over the plate with some regularity. He also has a good slider and a fastball with so much natural movement that catcher Joe Mauer likened it to a knuckleball. For batters, it's even more perplexing. But if hitters know he can't throw it for a strike, well, game over. Deduno swears he can. "Every start, my confidence grows," he said. "Then I say, 'I know I can do that. I know I can pitch a good game.' But I know not every game is going to be good, or perfect. Sometimes there will be a bad game, sometimes a good game. The thing I want to control is not walking people. I know I can control that."