Why Doesnt Pacquaio Fight Berto?

here let me finish,

Collazo and Ortiz, both south paws one with high work rate and no power and the other with power decent work rate but questionable chin and heart, both were able to beat berto both were able to hurt berto, Manny who is another south paw though on the decline, would utterly end Andre Berto kid gets hit too much and his chin is shaky