His punches are too wild and wide, and his defence isn't great at all...he also sometimes slaps with his punches.
I just saw his last fight where the guy lasted 2 rounds and Valero looked amateurish to say the least, a good slick boxer imo would beat him easily.
You could already see that he was breathing hard in the first round because he couldn't knock him out ,and was even worse in the second. He took good solid punches and counters because of his poor defence....
Imo, he's the crap version of Ricardo Mayorga