Everton were left exposed at the back when Phil Jagielka was sidelined through injury this term. Ramiro Funes Mori improves marginally with every game, but having more options in this area might have prevented the Blues from shipping so many goals in recent weeks. Then theres the issue of John Stones potentially leaving for pastures new, with a host of big clubs still circling the England international. More defensive back-up is needed, and Martinez could do far worse than out-of-favour Arsenal man Calum Chambers. The Southampton academy product is said to be growing frustrated with the lack of first-team opportunities at the Gunners, coupled with Arsene Wengers reluctance to play him in his preferred position in the heart of the defence. His chances of first-team football at Everton would likely be stronger than at Arsenal, but it may take a Stones windfall to bankroll a potential swoop for Chambers.