"We feel comfortable with the guys we have now, and we feel good about the two other guys that are potentially coming back," said manager Bob Melvin. "We've always felt good about our depth."
But how will they use it?
Though the A's have considered bringing back Anderson as a reliever, news of Colon's injury now has them in position to keep him in a starting role.
The A's will decide whether the Anderson returns next week soon after his rehab start on Thursday with Class A Stockton. He's slated to throw around 65 pitches, so he'd likely be limited to 80 his first time out with the A's, should they start him.
But Bob Melvin is not ready to commit to a return date for his Opening Day starter, only saying the lefty "could be" back after Thursday's outing, noting health is the most significant factor.
"We also want to make sure there's crispness on his pitches," he said. "Usually, when he's healthy, that's there. Trying to get his arm in shape, make sure the foot is in the condition it's in, and then we'll make a decision on what to do with him.
"We'll monitor everything. I don't think the results are the most important thing. We feel good about the stuff that he has. Until he gets done and how he feels and what we hear with life on his pitches and so forth from the people that are watching him, that will impact it, but to this point, everything that we've seen so far would suggest that he's almost ready to go."
Whether it's Anderson who comes back first or Colon, it's likely Tommy Milone would be the player sent down to Triple-A. Milone would likely be back soon after when rosters expand in September, though his role may be as a reliever.
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.