I was thinking they'd just dh for the first inning. Then every subsequent inning that player has to replace each fielder. Pitcher is not involved. It's a wacky idea overall, but could really play into the hands of sharp managers who utilize their flyball and groundball pitchers around which inning they sub out the regular at each position. For example, if your dh is an outfielder normally, you wouldnt want to have him subbing for the infielders early in the game if a ground ball pitcher was your starter. Then bring in a fly ball reliever later when the DH has to sub out the infielders. An all around type like a Ben Zobrist becomes crucial to a roster to minimize the defensive liabilities while still providing adequate offense. It keeps the DH and eliminates pitchers and their poor hitting, whole also eliminating the DH being h.o.f. worthy. You'd basically replace the DH with a new "position." A David Ortiz type is now not a solely beneficial player as his incompetence in the field is now a requirement, which promotes players being adept in all facets of the game.