Thomas is quite stocky. Also looked great in a couple matches when he came on that I watched. Use sparingly, ease him in (as with most youngsters) and I don't think you can go wrong.
Thing is, you could move Root up 4, put Moeen in at 5 and bring Rashid in - depending on the pitch. We've got options. But I definitely agree about Bell. Shame, he's a belting player when he's in form.
Lunch has come at the wrong time. Ballance was just getting into it and Johnson was getting smashed around a bit in his last 2-3 overs. Watch a couple wickets fall quickly after lunch now!