I think he is. Certainly he hasn't been himself this season (he was better in his first season, and that was a slow-mo horror show compared to the way this one's going): and although I can appreciate that he brings a lot of hard-running and intelligent positioning to the team that is often overlooked, he does currently seem slower to react to defensive lapses, slower on the ball and more hesitant with his final delivery, all of which point to fatigue being a factor and all of which should put his position in the starting eleven under serious scrutiny. Maybe he just needs the rest, or maybe he's just in a bad patch of form, like Kane was at the start of the season - in both cases, we've seen that the players involved still made the hard runs and pressed for opportunities, but were more hesitant and wayward when on the ball and made the wrong decisions when off it. Either way, dropping him is starting to look like a necessity.