Not saying Deeney hasn't deserved the punishment but I think Allen should also have been punished more than a yellow. He launched into Deeney and not in the way Westander suggests.
It's a bit nasty but let's not forget it was initiated by Allen who persisted coming to Deeney. Stoke were annoyed that Watford didn't give the ball back but the Stoke player wasn't really injured just time wasting as Stoke were in the lead.