"That's the range," Phillies player development director Joe Jordan said. "We'll see in a few days how he responds to treatment. We'll have a better feel in five, six, seven days from now."
Crawford, 20, had been scheduled to open the season with Class A Advanced Clearwater or Double-A Reading.
"It's disappointing, but it shouldn't be a long-term thing," Jordan said.
The Phillies selected Crawford with the 16th overall pick in the 2013 First-Year Player Draft. MLBPipeline.com ranks him as the No. 22 prospect in baseball. Crawford hit a combined .285 with 23 doubles, 11 home runs, 48 RBIs, 24 stolen bases and a .781 OPS in 538 plate appearances last season with Class A Lakewood and Clearwater.
Todd Zolecki is a reporter for MLB.com. Read his Phillies blog The Zo Zone. Follow him on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.