I'm not quite sure I understand the shouts of 'he's not bad so why don't we just see if he's any good with a run in the team and then get rid if he's not'. Well, because if he's not, then we'll have just wasted a year won't we? So would it not make sense to bring in someone who we know is better in the first place?
Don't get me wrong, if Martinez (or his replacement) see Joel as a potentially top class keeper then fine, keep him. They know better than me obviously. But keeper is a very important position, and my personal opinion is that there at least 8 keepers in the league who are clearly better than him, and only a couple who he is definitely better than. We weren't happy when Osman and Hibbert were playing and they were the 9th/10th/11th best players in their position, so is there a reason why we'll accept it from a keeper?