Neither should be doing it, more to the point. Shouldn't be allowed to get away with it.
5 pens, book them for the very first instance, tell them it will result in a red second time.
But you wouldn't throw a kid on would you if your backs were against the wall. A not fully fit senior player is going to be a better bet if it's a last resort you would have thought.
We all know his substitutions and timings of the substitutions has proved to be an Achilles heel at times. It just has. That's his biggest weakness without doubt.