DC doesn't have the reach to slap his fingers away. OSP has height & reach closer to Jones, which is the kind of fighter Jones has trouble finishing (or poking).
Cormier's short ass will just have to deal with it, & use the Three Stooges defense until he gets into clinch range.
I'm no scientist but I'd venture a guess that you don't have to have too long of a reach to slap away a hand that is six inches from your face.
Doesn't matter though, Cormier is getting wrecked at distance or in the clinch.