Howie Long. . .
Wasn't any worse than many of the other more successful meat heads in their first leading role.
-Arnold in Conan the Barbarian- Mostly grunted and hacked people up with his sword
-The Rock in Scorpion King- Same deal, but had a bit more dialogue
-John Cena in The Marine- No one would say he'd be doing movies for another 20 years
I think Howie just wasn't willing to keep at it after Firestorm, take secondary roles to work back into the bigger roles, etc. Or maybe he just didn't want to take steroids at the age of 40 so he could look the part, unlike the guys mentioned above.