"He's basically played with it for the last two or three years," Pagano told the Indianapolis Star. "He didn't know he had it. When we brought the rookies back for that three-day period, he went out the first day and had a better day than anybody else catching and running routes. He went in the locker room and cut off the tape and was hobbling around. We expect him back shortly."
Whalen will be fighting for a roster spot; he signed with the Colts as an undrafted free agent in April. After walking on at Stanford, he led the team in receiving yards and scored four touchdowns as a senior.
Indianapolis drafted another one of Luck's targets at Stanford -- tight end Coby Fleener -- in the second round.
For more up-to-the-minute news and analysis from Colts blogger Evan Hilbert, follow @CBSSportsNFLIND.