Figure we should probably continue this in the topic made for it.
I'd define "success" mainly in ecomomic terms - do you attract fans with your play? Fans like a team that wins, of course, but also one that shows the capability of winning. It isn't just about championships, nice as they are - the Vancouver Canucks fanbase is loud and dedicated, and I don't think they've failed to sell out a game in about a decade; they've never won a Stanley Cup ever - it's about making your fans believe you could nab one. In that regard, the Braves certainly experienced success; quite apart from the fact that they -did- have a World Series title in there, they threatened for many more. I somehow doubt they had too much trouble selling tickets or TV deals, or that they lacked for people in Atlanta talking about the Braves (or, for that matter, people outside Atlanta; they were a pretty darn popular team).
A system thus should encourage situations where people believe their teams have a legit chance to win, since it's pretty clear fans like that.
You approach things like a hardcore fan of the game, which is fine, but keeping people like you happy isn't what sports are in the business of; you'll follow them regardless. If the way a sport operates is losing them their more fickle casual fanbase (as baseball is), chances are they're doing something wrong.
The thing is that the tightwad teams still make a notable profit even with a tiny fanbase because they spend so little (Marlins), so they're not about to change if they don't have to. This is where a salary floor would help, more than a salary cap would. Forcing the Yankees to spend no more than $150 million a year is not going to make the Marlins or the Pirates spend any more than they already do.
I recall both Boston AND New York management being on record as supporting a system that instituted both a salary cap and a salary floor, and that it was the management of lesser-spending teams objecting to the idea because they don't want a floor.