As fun as it would be, the way England seems to pick its top order is actually a joke.
I mean, take Mascarenhas, for example. He looks like he will be in the side for a long time, not because he's an great bowler or batsman, but because he plays his roles. His bowling is restrictive and he adds quick runs at the end of an innings. If you were to put him in the top order though, I'd have to slap you.
England are trying to manufacture a dynamic top order in both ODIs and T20s, instead of one made of great top order players. They can't pick Mustard, who doesn't average over 30 in any form of the game, and simply demand he becomes Gilchrist because he now plays international cricket. It's a waste of an otherwise useful player.