Bob Arum and co thought it would be OK to pitch Pavlik in with Hopkins as they thought he doesn't use his weight against his opponents as much as some fighters do. Didn't matter thou, Hopkins beat him with speed and power.
To give Arum his due Hopkins wasn't the first pick for Pavlik. I'm sure I read that he was about 9th choice, he was short of options for any decent (and well paid) match-up.