If you eliminate Thornily on the grounds that a) You want Moore in the centre, and he's wrong-footed to play RCB, and b) He's been crap recently, then the position came down to Smyth vs. Long
In my view, Smyth offers you massively more in terms of passing range and attacking threat, but Long is the better defender.
We're playing the league's second top scorers, and form team......so it doesn't hurt to go that little bit more defensive.
Think I'd have done the same.