why did zab stop throwing?

[beez721]

the first 3 rounds he had cotto hurt twice, 3 times total in the fight. zab was landing the left uppercut easily and snapping cottos head with each shot. why'd he stop throwing the left? it wasnt like cotto was making him pay for throwing it, zab hadn't been hit much up to round 4 and was hitting cotto at will. after round 4 it was like he kept waiting and waiting and never threw a meaningful punch

he's always been a 4 round fighter. he cant fight at a descent pace. cotto was just too much better a fighter than him,,,like kostya,,mayweather and even baldimr