Even still, just because of those, it doesn't make it that hard to win. To be honest, if I were to do a FFA with Phoenix (without them targeting me off spawn) I could say without being arrogant win at least 3-4 games out of 5-6.
Majority of people with good w/l play majority of their games safely, try to reduce as many risks as possible while they play extremely strategically. It's the main way people win games. Many people like stated previously have good ratios because of alts. Would you have a good ratio on Bloodlights if you hadn't played on TorchScar first? Correct. Many people that do have a good ratio on their main account were actually decent and knew how to play before they started (other PvP, or faction servers) and evolved their strategies even more than before (fishing rod etc.). They must of known the basic mechanics of the sword and bow. In a matter of fact I didn't know that you could block with a sword or what flint and steel was. I'm assuming majority of the people in the top 100 with good ratios knew how to play strategical PvP (excluding myself, it could be way better then what it is).
It's not to much of a ramble of what it could be, however many members I know (including myself and Darkrai) had horrible ratios ~1/10 1/15 ratios, but know look at how much we've improved and the way our ratio has changed to. I'm now winning at least 3/5 of my games and changing my ratio bit by bit.
However, as Darkrai stated, some guys with good ratios do either win boost (cough flabbypenguin cough) or go around in large teams just to feed and it gives them a good ratio in the process, and I've seen it myself. That's why I'm out to prove that I don't need a team to win by leaving Phoenix, because people in AU just happened to always see me in a team, and I've currently proved them wrong.
As for what I consider a quite a good ratio (with at least 300 wins) around %40.