Robles replaced Al Hasbi as Wigans number one for their run in after they knocked us out the cup, he conceded an average of 2 goals a game. He's one of the reason Wigan got relegated really.
The semi final will be Martinez most pressurised game ever, the cup final for Wigan was a free hit and in reality so were his relegation scrapes. Nobody ever expected little Wigan to stay up for ever and nobody gave them a cat in hells chance against City so he could stay loyal to his players safe in the knowledge he'd be the good guy whatever the result.
However expectations and desires at Everton are completely different and he's not going to send out a deliberately weakened team against the best side in the country in a semi final. This is his one shot at really achieving something that will make people sit up and take notice, it's the launchpad for his career. He won't throw that away on a gentlemans agreement or blind loyalty he'll be ruthless and play his best and strongest team available, which as well all know means Howard in goal.