Kelly, who was one of the pieces the Red Sox shipped to San Diego in exchange for Adrian Gonzalez in December 2010, will take the ball for the first time as a member of the Padres on Monday night against the Braves. The start comes just days after the Sox shipped Gonzalez to Los Angeles.
Kelly is the Padres' top-ranked prospect. He was ranked 76th this past winter on Baseball America's Top 100 prospects list, and was viewed very highly during his time in the Boston organization. This season, he's pitched at three levels in the San Diego system, going a combined 0-2 with a 3.35 ERA in eight starts.
"There are major league debuts across the landscape of our game, almost daily sometimes," Padres managers Bud Black said Sunday. "With Casey, it's a little different. He's more of a higher-profile guy but I don't want to put too much weight on [Monday's] game just because it's unfair for a lot of reasons. We saw it here in Arizona when Trevor Bauer made his debut. It's one game."
The 22-year-old Kelly pitched his entire 2011 season at Double-A San Antonio, going 11-6 with a 3.98 ERA in 27 starts.