How is Martinez too big for Mayweather?

[The_Sandman]

I believe Mayweather can defeat Sergio Martinez. As a fan I want to see that fight. But if I were the fighter...that's kind of ****ed up. Mayweather vs Martinez at 154 is fine. But the problem is...what comes after? Andre Ward? Hopkins?? Then the Klitchkos? And if he doesn't fight them he's ducking and dodging?? See the problem is people are always going to wonder what's next.