"Right now it is what it is," Duncan said, "until it changes."
The Cardinals have yet to announce a starting pitcher for any game beyond Sunday's series finale at Fenway Park, though Braden Looper is expected to start the Tuesday night opener in Detroit. The rest of the Tigers series, however, remains uncertain thanks to a number of moving parts.
Kyle Lohse could pitch on his regular fifth day on Wednesday in Detroit, or he could benefit from an extra day of rest after the team's off-day Monday. Todd Wellemeyer, recovering from right elbow pain, could slot in on Wednesday or Thursday. Duncan didn't even rule out the possibility that Mark Mulder's next start could be for the Major League club.
Wellemeyer is likely the biggest variable. He's expected to throw a bullpen session on Saturday and then another on Tuesday. If both of those go well, he hopes to return to the starting rotation on Thursday in Detroit or perhaps next weekend in Kansas City. Wellemeyer has made one start since June 5 as he deals with discomfort in his right elbow.
"I don't think it's going to be very long," Duncan said. "He's been playing catch and his arm feels good. [He'll get] whatever he needs. When he throws his first bullpen [session], we'll see how it goes and how he recovers from it and we'll go from there."
According to Duncan, Mulder's most recent Minor League rehabilitation start was better than his final line would indicate. The lefty, who is recuperating from shoulder surgery, was raked for six runs -- all in the first inning -- on 10 hits with three strikeouts and two walks in 3 2/3 innings.
"He said he didn't have real good command of his fastball," Duncan said. "But the whole time he was out there, [Memphis manager Chris] Maloney said there were only a couple of balls hit hard. There were six or seven ground-ball hits, which is his game."
It appears more likely that Mulder will get at least one more start at Memphis, but Duncan said that's not a certainty, despite the rough result of his last game.
"He felt good about it, according to what he told the trainer," Duncan said. "He recognized that the hits were on the ground, and a couple of broken-bat hits. He struck out a couple of guys. I just need to talk to him myself."
One pitcher who does not figure in the discussions is Matt Clement. The right-hander is eligible to make three more starts on his 30-day rehab, and it appears that he will make all three. Clement is still in a lengthy recovery process from shoulder surgery he underwent in 2006.
Matthew Leach is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.