It's difficult to know with Tsonga. Had he won his maiden Slam at 2008 AO, it might have given him the confidence he needed to go on a roll and surge to the top of the rankings and win a few more.
Then again, since winning his maiden Masters title in Paris at the end of that year, he hasn't won another.
He just doesn't seem to be consistent enough, mentally or physically.
"I have to apologise because I clearly pushed Roger so hard on Thursday!" (Andy Murray on why Federer couldn't play the WTF final).