With Josh Beckett traded over the weekend and Franklin Morales on the disabled list, a spot opened, and the Red Sox will use it to get a look at Stewart.
The 25-year-old Stewart pitched in 18 games for the White Sox this season, posting a 6.00 ERA. Just one of those outings was a start. The Red Sox hope to develop him into a starting pitcher.
Stewart has made 11 starts for Triple-A Pawtucket, going 3-5 with a 3.94 ERA. Over 59 1/3 innings, he had 14 walks and 52 strikeouts while holding opponents to a .252 average.
"I felt like I started off strong," Stewart said. "I had a couple of rough outings in the middle, and I've been doing well lately. It's one of those things. It's just starting. It's how it always is, just try to stay as even-keeled as possible."
The Red Sox will now get a chance to see what they have in Stewart.
"There's very little I can say about him other than the reports I've read, which tell me he's a good competitive athlete with a good sinker, not afraid of contact, likes to play the game of baseball," manager Bobby Valentine said. "We'll be excited to have him out there."
Youkilis wasn't the first big-name player Stewart has been traded for. Back in 2009, he was traded along with Edwin Encarnacion from the Reds to the Blue Jays for Scott Rolen. The Blue Jays packaged him with Jason Frasor in a 2011 trade to the White Sox for Edwin Jackson and Mark Teahen.
"There's always a silver lining to it, because somebody wants you and somebody is giving up something to come get you," Stewart said. "It was a big trade. To give up someone like Youkilis and what he brings to the table and what caliber a player he is meant a lot to me to come over here that they thought that much of me to give up a guy like that."