He last started against the White Sox on Sunday and faced three batters in a sixth-inning relief appearance against the Athletics on Tuesday.
"Well, we like his power," Yost said. "He's on regular rest. That's his fifth day. Last night's game was like a side session for him. You know, the kid's got power. That's what we like about him. He throws a 100-mph four-seamer, a 96-mph two-seamer, 95-mph cutter, a nice changeup and above-average curve when he throws it for strikes, so we like his power."
Yost said James Shields will pitch on Sunday in Game 3, and then he would make a decision on the rotation after that. Jeremy Guthrie and Danny Duffy are expected to be in the bullpen early in the ALDS.
"Well, in the playoffs, every pitch is a high-intensity pitch, every inning is a high-intensity inning," Yost said. " And I think you find more during the playoffs that starters generally don't go as deep as they do during the regular season. So you've got to have that depth.
"You've got to be a little bit quicker, I think, with your trigger finger, so you've got to have somebody who can come in and pitch long in a situation, and Danny Duffy, with his stuff right now, we feel that he's going to fill that void. Now we'll get down the road and see if a spot opens up for him to be a starter, but for the first three games, he's going to be in the 'pen."
T.R. Sullivan is a reporter for MLB.com. Read his blog, Postcards from Elysian Fields, and follow him on Twitter @Sullivan_Ranger. This story was not subject to the approval of Major League Baseball or its clubs.