Why do people think Zab is such a powerful puncher?

He tko's people by swarming them. He's not a ko artist. He bum rushes guys in the first 3 rounds and if they survive that he's not very effective.

Cotto has a great chin. Getting rocked doesn't mean anything. He didn't go down and he recovered quickly. Torres pushed Cotto down. Watch it again.

Cotto will break Zab down. Zab doesn't like to get hit, and his chin is shaky. He takes a very long time to recover. Cotto can give and take and is very durable, Zab's not. Zab will land a few good shots, but he's getting ko'd. He might throw a low blow on purpose when he's on his last legs and knows Cotto is coming.