The Phillies placed him on the 15-day disabled list Tuesday because of inflammation in the shoulder. He battled shoulder problems during Spring Training but the Phillies said they think this problem might be different.
"It could be related. It could not be," Stutes said Wednesday morning at Chase Field. "I have no idea."
Stutes, who last pitched Saturday in San Diego, said he has felt some discomfort in his shoulder for a while.
"It was just kind of a weird feeling," he said. "It just didn't feel right. I wouldn't say it was excruciatingly painful where I couldn't hold the ball or anything. It's not anything like that. It's just not right. It doesn't allow me to throw how I normally throw."
Stutes could have a MRI exam Thursday in Philadelphia.
Right-hander Michael Schwimer replaced Stutes on the roster. He was 1-0 with a 1.04 ERA and two saves in 8 2/3 innings with Triple-A Lehigh Valley.
"Yeah, the numbers -- they were good, but nine innings isn't a sample size that can qualify as throwing it real well or anything like that," Schwimer said. "In terms of executing the pitches I want to execute, much, much better than I was last year. I'm very happy with how my game's going right now."