"As I sit here right now, I really couldn't tell you that," said Melvin. "As a manager, you try to put guys in positions where they can do well, and I don't know that bringing him in the middle of an inning is putting him in a great position based on how he prepares for a game, his routine to get ready.
"He's willing to do anything we want him to do, I'm just not 100 percent sure I want to put him in a position like that."
Melvin, in conjunction with the rest of Oakland's brain trust, made the gutsy decision to start rookie Sonny Gray over Colon for Thursday's winner-take-all affair. Gray made it through eight scoreless innings in Game 2, and his ability to rack up at least six or seven innings this time around would prove highly beneficial for the A's.
"I'm not going to have him throw 130 pitches," said Melvin, "but he's thrown 116 and 111 last time out. So he's capable of throwing some pitches."
Right-hander Jarrod Parker appears even less likely than Colon to make an appearance in Game 5. Throwing on the field for the first time since his Game 3 start on Monday, Parker was deemed just "all right," according to Melvin.
"Whether it's just kind of a long season, maybe he's getting a bit of a dead arm right now," he said. "He'll probably get on a mound today if he feels good, but we'll see."
Jane Lee is a reporter for MLB.com. Read her blog, Major Lee-ague, and follow her on Twitter @JaneMLB. This story was not subject to the approval of Major League Baseball or its clubs.