Rarely have I beaten someone ranked above me in USFIV. Sure, I’ve beaten a couple of C+ ranked people with a C ranked character, but I’m talking about, let’s say, a D ranked beating an A ranked. It seems like 99% of the time you get matched-up against someone higher ranked than you, defeat is inevitable. I did once beat an B ranked E. Honda with a D ranked Ryu, though… but that’s because the connection between me and the other player(I’m from western Europe and he was from Japan or Korea, don’t recall) wasn’t very good and the game lagged like hell. In fact, I pulled some moves without really knowing what I was doing and I bet he did as well. We blocked a lot and kept our distances. It was kinda funny, to be honest.
Anyway, I dunno about other fighting games, but it seems to me that you can’t really depend on luck in USFIV at all. The only “luck” you might have is your opponent making mistakes. Although, obviously, a B ranked opponent will not really make many mistakes, especially not against a D or even a C ranked opponent. Even if you begin timing your blocks well, you’ll still feel like you’re facing an immovable object. I guess it depends on the series, too. I would not be surprised if in a game like Mortal Kombat, per example, a player could depend more on luck. But feel free to correct me if I’m wrong.