I'm not putting a definitive points tally on it, but Howard has not been on top form this season, and possibly last season.
Whether Robles would've made a difference we'll never know but last season he had 3 games on the run and kept 3 clean sheets. For me, he deserved a run then.
Now that (for most people) Howard is less than excellent, surely it's time to give Joel a try? Otherwise what's the point in him being here?
I'll admit we probably compare every goalie to Nev, who was the best in the world (tm) so all goalies will fall short of our idol but for me and a lot of others, Tim Howard is not playing well - Martinez may even be damaging his confidence by not giving him a break.