BJ is more mental than anything. He's never been knocked out cleanly...only TKO. Even still his face was fine that was until Diaz. Rory is a terrible matchup. BJ simply gasses out in the third and it's game over.
GSP and Fitch ****ed him up pretty bad too. Not nearly as bad as Diaz did, but it still wasn't pretty.
Add that I think Rory has way more power GnP than Fitch or GSP and he's crazy accurate with it too. I'm going close first four minutes, unless Penn gets taken down, which is possible, and it's all over from there.
Also how is it for sure roids? Seriously...he's 23 for gods sake, just about every man fills out in his mid 20s. He's at a real gym now and he's getting older. Everyone forgets he was 20 when he showed up in the UFC and was jacking people as a skinny little kid.