So...Where did Steve-O go?

My brother just brought this up and I've been wondering the same thing. I kinda watched the show when he was on it because I'm a Steve-O/Jackass in general fan but now it's got Mark McGrath, who has no personality and is just plain boring. So does anyone know why Steve-o didn't return for the second season?

Loathing is my life blood, rage my royal jelly