Not sure I'd go as far as picking all the greats to beat him but it really is hard to see a guy so careless/clueless/wild, that is struggling with below elite class competition having much success against modern greats.

Just look how he CONSTANTLY squares up and rightly gets punished? He is literally running face first at fighters. To his credit he is crazy tough, but it's hard to envisage a Mosley, Oscar, Kostya, Floyd, Pac, etc, not making him severely pay, he's begging for one straight down the pipe, the difference being I highly doubt they'd let him off the hook.