Whichiwhichi,
You have made some great points. Teams who are strong and dominant on the field will keep the ball away from the keeper soo much, that he will hardly see the ball. The point you made about a keeper having high percentages, especially on shut-outs, is a great point. Just b/c they have a great shut-out percentage, doesn't mean that they are the best in the state. People love to "put teams/people on blast" when the team gets their tails handed to them, especially the keeper. The keeper will get shelled, and then people tend to think the keeper sucks, which is not true all the time.
I know personally. When I played keeper for my team, I would get shelled every game, with the exception of two or three games. I made those 20 to 30 saves a game, and that is not exagerating either. If a keeper is making 20-30 saves a game, eventually something is going to get through. It's just simple math. Here's one of many examples I'll use: When I played Summerville my sophomore year (they were a lot better back then then they are now) I had 15 breakaway 1-on-1's and I had saved 14 of those 15. So it shows where my defense was at the time huh? Final score was 3-1 Summerville. My total saves count for the 4 years I played high school soccer was unreal, a total of 857 career saves. A keeper shouldn't have to make that many saves.
You got to acknowledge keepers of low caliber teams too, only if they deserve it. I'm not saying that all low caliber teams have the best keepers, but you can't count them out, and you can't count out keepers of high caliber teams either. In reality, like whichiwhichi said, there isn't really a way to rate a keeper unless you seperate all of them from their teams and rate them in some sort of "Keeper War" or competition in order for their true colors to come through. That would be the best way to name a keeper "the best".
