Being a former stoner myself who now completely abstains Id have to say that playing on weed vs. playing with a few beers in me vs. playing completely sober are all about the same. What really matters is when you focus and relax enough to get into the game and it usually has to do with other factors (like familiarity with a particular machine and warmup time)rather than substances. I have to admit (and I was guilty of this in the past as well) that stoners tend to say they are better at X when stoned about any number of things to justify an addiction. The drug makes you sort of out of it in a similar way to alcohol but can relax you enough to get into a zone.