I'm almost certain he was calling it quits after the season. However, no one likes to go down like that. A personal story: I was 43 and ready to give up softball. I'd been thinking about it for a year or two and finally told my teammates that this was my last season. I'd played with most of them for 10-12 years so I felt I owed them that. Then I tore a calf muscle chasing down a flyball. You can't "play around" a torn calf. I missed all the big state tourneys in the summer. That was supposed to be it. Limping off the field in your "last" game might not have been a big deal to most but it didn't sit well with me. So I set my sights on the fall(which I hadn't played in a couple of years) tourneys. After representing myself well in a dozen or so games, I decided what would be my last tourney. After our first loss(double elimination) I told my teammates again. In a blowout in what was to be my last game, the other teams pitcher threw a couple of balls to the batter in front of me with 2 down, runners on 1st/3rd, bottom 5th(we were getting 10 run ruled). The 3B, a long-time teammate and friend, yelled "You're about to walk yourself in a grand slam. T23 is gonna put your **** in the woods if you walk that batter!!!" He did, I did and that should have been my last AB in our 19-7(or something like that)loss. Except a couple of people said "You're not gonna quit now, are you? The OTHER team is calling your shots." Now I'm chasing that moment at 49.
So, the point after my long-winded story, is that Rivera might be chasing a moment. If he is, and he can still be effective, he'll come back. After all, it wasn't his arm that blew out. There won't be any wear and tear on it. Pettite is apparently doing well after a season off.