He has. There's something maddening about him, though. Unlike Zebina, who can play like complete dog crap for four solid months, Boumsong can alternate from having a decent match one day to doing the most imbecilic, boneheaded thing the next match.
If it were merely a question of having no talent, he should not be able to play any matches well. Instead, there's a real problem with his consistency and in what I can only describe as complete mental lapses during his play. His play is at best, decent, with regular bouts of unexplainable, maddening foolishness thrown in on a semi-regular -- and unpredictable -- basis.
Even if he could pick up his lapses, I question whether he'd even be strong enough for the bench in Serie A. But it's clear to me he is capable of playing better than most people give him credit for.