Melvin said Wednesday he is "thrilled" the right-hander will return to the club next year after his 2012 season ended with a 50-game suspension Aug. 22 for testing positive for testosterone.
Colon received a $3 million, one-year contract Nov. 3, though he still has five games remaining on his suspension when the 2013 season starts. While the new deal includes incentives for starts and innings, he also has potential bonuses for relief appearances -- though Melvin said Colon would prepare as a starter and will be "embraced" by the reigning AL West champions.
"He's gone through his penalty," Melvin said. "It's one thing if it's a guy who might be a little bit of a bad guy, but his is a true gentleman, a great guy who just made a mistake. He'll be embraced back here again. He was very important for us. Guys like that can kind of get lost in the shuffle when they're not here and you get to the postseason, but he was a key guy for us, he really was."
The former Cy Young winner went 10-9 with a 3.43 ERA in 24 starts for Oakland last season, his 15th in the majors.
A's general manager Billy Beane said finding a veteran pitcher to be part of a young rotation -- and for the financial value -- Colon was the perfect fit.
Melvin said he last spoke to Colon about three weeks after the suspension began, and they will talk again before the start of spring training in February.
"I don't need to talk to Bart. I will call him at some point in time," Melvin said. "I got very close to him, and we had a nice conversation and he was very remorseful when all that went down. I think in the back of his mind he was hoping this situation would arise for him again, and it did."
A's assistant general manager David Forst said Wednesday the team remains in contact with shortstop Stephen Drew. Oakland declined to pick up their half of a $10 million mutual option late last month. Drew is seeking a long-term deal.
"We're still in touch," Forst said. "We're looking to do something at that position, and he's still an option."