Simon Hughes actually made an interesting point on TMS today about a possible reason for Prior's troubles in keeping to Sidebottom who 90 percent of his drops seem to have come off. His starting position is not far enough over to the offside which means he is infact unsighted at the point of delivery. Given Prior doesn't have the greatest footwork in the world he really can't afford to lose those few precious moments before he picks up the line of the ball and it's no surprise he seems to be in far worse positions to take the ball than he is off the right arm quicks.

I guess it's a bad habit picked up from keeping to Lewry who as well as being much slower and gets much less carry (which gives him more time to get into position) also swings the ball in considerably more than Sidebottom hence the tendency to favour the legside. Still it's a small technical detail that you really would have hoped that the two keepers Flower and Moores would have picked up on and rectified by now.