I don't understand the logic of playing Roberts on the right. He's so left footed that the defenders know he'll cut inside, so he's running across the field all the time. That makes crossing that much harder, and there are very few targets to aim for anyway.
Roberts would be better played as a left winger or behind the front two, in the middle of the park.
Then Play Tavernier on the right, Coulson left and Howson as the defensive midfielder.
Then perm any four full backs and centre halves from Spence, Friend, McNair, Fry, Shotton, et al.
The crucial thing is to score goals now, goalless draws just aren't going to do it with six games to go.