tough to get knockouts when you're a former flyweight fighting the likes of Margarito, Mosley, Clottey or Marquez
To be fair though, had he fought those fights in Britain, he would have had more KO's than actual fights.
He TKO'd Margo and Algieri but the ref just wouldn't call it. Watch the fights, they were easily TKO's.
In his 9 fights since the KO win he has dropped 3 of his opponents, though. Had they been more offensive and tried harder to win throughout, he likely stops some of them (although this can be said of most dominant fighters).
I think we all can agree that the Margarito fight should have been stopped. The ref permanently ruined Margarito's career.