Then that merely takes an absolute and turns it into a trend; the better players will usually (instead of always) outperform the good ones.
But any factor you care to list isn't a matter of skill. Character building? No skill needed when you can read a guide. Tactical combats? Matters just as much if not more what kind of tactics the DM is using, and even then the plan of "hit them til they stop moving" tends to work pretty well. Tapping every inch with a ten foot pole? Basic paranoia that anyone can come up with.
And, again, any combat plans can be failed by a d20. Any plans to avoid traps can be failed by a d20. Any game at all can crash and burn because the DM overestimates you and they make a mistake. No amount of "I'm a good player" actually does anything to lean you towards good outcomes.