Apparently it's because he says Elano has been shite lately and he wanted to go with a "different group" of players and "give Clayton a taste of being around the first team squad". Pile of shite, Hughes, pretty obvious he's lying.
Source is Post match interview with the BBC http://news.bbc.co.uk/sport1/hi/football/match_of_the_day/7794728.stm
Source is Post match interview with the BBC http://news.bbc.co.uk/sport1/hi/football/match_of_the_day/7794728.stm