Originally Posted by Beriac
If you mean someone who doesn't do the math but tries to use discipline based on experience, I could see that player doing reasonably well too.
I agree. You can still do the right thing without knowing exactly why. I mean, there are all sorts of "tips" that are based on odds and equity, but don't actually reference them. Like "small pocket pairs are okay to play before the flop if you can see the flop for less than 10% of your stack" is of course based on the idea of likelyhood of hitting a set, vs. the large implied odds that you have if you succeed. You don't have to know the odds of hitting a set to "learn" how to play small pocket pairs.
"Suited connectors play better in multiway pots" is another one of them. I'm sure I've read somewhere that you should avoid chasing flushes in heads-up pots as well. It all boils down to the same thing: Using "standard plays" as a crutch that allows you to not actually care about the odds, but mostly make the right plays anyway.
Edit: I chose "mediocre." You can still be a winning player at lower limits without knowing much about odds, but playing according to pieces of wisdom like the ones I quoted above. As soon as your competition becomes tougher, however, you need to be able to extract value out of situations where the line is not as clearly drawn, and then you need to be able to look at your hand, your opponent's probable hand, the size of the pot and the odds that you're getting, and make a play based on that information.