The loss of Brown and the fact we didn't sign a RB have probably been the biggest motivators behind the push.
If Brown had not retired and we'd signed a RB, i imagine Fenton's playing time would have been quite limited with Bertos going back into a RM role which probably would have pushed Ifil more central cancelling some of Boyd's opportunities.
Brown's departure allowed Manny to go central which caused the need for the Bertos stop gap (will call it that until i'm convinced otherwise). And it also means Lindsey effectively is the back up DM (although with LIa back he'll drop in pecking order).
I also think its easier for Ricki to give attacking youth a run.... because they can't cost you a game the same way defenders can through making errors, and sometimes youthful exuberance can be rewarding.
Will be rewarding..Fenton>Sanchez and Clarke>Sanchez..and Boyd when his time comes.