Ol' Ronnie forgets that Coach sees every player as a single resource, and bundles certain ones together as a team based upon which opponent New England is facing that particular week.
In the Military, we would refer to White as a "force multiplier" last weekend. He didn't get any touches (IIRC) but he added a great deal to the blocking scheme, both in protecting TFB, and helping the other RB's get open. His value was greater in that position than as an RB, for THAT particular game. He increased the overall strength of the O-Line by his support out of the backfield. That'd why he was used in that manner.
Come the SB? Who knows what Coach will dream up. But whatever it is, it will utilize the 43 players that the Coaches feel best address both the threats from Atlanta, and the scheme that New England intends to counter it with.
Each man has a set of stats that are unique to him. The true genius of Coach Belichick and his staff has been the ability to continuously and successfully bundle those individuals together, each week, to get the best possible matchup against a particular opponent.