Originally posted on 03/31/2015:

It's not 1500 hands against the same player or table, its 1500 hands at a given stake level, based on your past performance at the same stakes. The bulk of players at any level will have the same skill level relative to their competition. 20%will lose, 60% will break even and 20% will make money.

Basically, if you are beating the game for 10BB after at least 1500 hands you should expect the same result in the future. And if you're down 10BB you should expect to keep losing that amount unless you try to improve. To me that's the very definition of skill.