Every character in Star Wars is over-rated by somebody.
We started talking about Thrawn, after all, who did in fact lose. Performance-wise, he's equal to Daala. Unites fractured Imperials, leads successful campaign, then gets scewed over by a factor that couldn't realistically have been predicted. In fact, we can argue that Thrawn performed worse, because he A) lost in his first campaign, whereas Daala showed at least a bit more staying power, and B) kept relying on bodyguards he was actively deceiving, which is usually a bad move (whereas Daala really couldn't have known that Jedi had the power to magically push a bunch of Star Destroyers to the edge of the system). Thrawn is just better-written, though. And he had way better publicity (also in-universe). So he gets way more credit.
And Boba Fett? Didn't he lose to an unarmed blind guy that one time?
It just depends on who we like best, and any character that's really liked by a bunch of people will be seen as over-rated by the people who don't like that character as much (or at all).