I think if anything the Diaz fight showed that he needs to not exchange punches with one of the most dangerous volume punchers in MMA. He implemented his kicking game way too late and let Diaz get in his head. Cerrone went out there trying to prove a point, which is never a good way to approach an MMA fight.
Cerrone is very good on the feet but has a tendency to put himself in harms way. While he definitely has a tested chin he also has been in quite a few bad spots in his career (especially in the Guillard fight). His defense is a bit lacking and Pettis throws everything much faster than Cerrone and is far trickier.
Cerrone is not going to be able to shoot on Pettis either or out wrestle him. Pettis generally has good TDD and that will be especially true against a taller fighter who's bread and butter is not wrestling.