Your definition of a championship-caliber player is very good. I'd add that such a player steps up in a big way at "money time" and actually I read that into your definition.
It's why, IMO, Peyton Manning is not a championship-caliber player. The only championship that really counts in the NFL is the SB, and Peyton has choked twice when those bright lights were on. I'm not discounting all players who have only one or even no rings. Some guys just play lights out when the pressure isn't high. The pressure couldn't be higher than in the SB.
In their only SB appearance (so far), ARod and CMIII stepped up when it was on the line. Championship caliber. That said, they need to cement this status with another ring, or two. At any rate, I like your definition.
As an aside, don't waste time trying to get into an honest debate with a couple of posters on this forum. These folks seem to have a need to "win the argument" when there's no argument in the first place, just an exchange of opinions. After banging my head against that wall, I've decided to not engage anymore with such insecure people. As I said, it's a waste of time. You seem like an honest, intelligent person. Nice to have that here for a change.