It makes sense what you say and does seem so obvious, I would imagine that Malky knows this but does not have a suitable replacement for Whitts, and does not want to change the formation, up till now?
Maybe he will switch over the rest of the season, and change things around, who knows?
One thing is for sure Malky is no fool and we are top of the league with a game in hand, so lets leave it up to him to decide how to play Whits and not some no mark scout.