Let's just say that I have my fair share of sports knowledge. A lot of this comes down to luck. Albert Pujols can hit a HR in game 1 and 3 of a series and you only took him in game 2. Meanwhile, a no-name player will go 5 for 5 in a game that Ryan Braun goes 0 for 5.
A lot of the participants live on these sites and are crafty. I like it because of the legality but sportsbetting is much better for a real handicapper, fan, etc.