Either way, Carroll heaved his support behind the embattled 49ers head coach Wednesday, something that few expected.
"I've never seen him not be a really good coach," Carroll said via ESPN.com. "He's a fantastic football coach. I've watched him do all the stuff he did at Stanford and turned that program around. What he's done at the Niners, I know that he's a great football coach."
It wouldn't surprise us if this is a general attitude shared by many NFL head coaches. Though they might dislike Harbaugh, they have a certain admiration for the almost maniacal way he lives and dies with his football teams. They might be scared to hire him, but they're terrified of coaching against him.
With Harbaugh working in California so long -- paralleling Carroll's rise at USC and in Seattle -- the two have plenty of reasons to hate each other. Last year's NFC title game would be good enough.
But, even on the verge of knocking Harbaugh out of the playoffs for good, Carroll is able to put that aside.