4. Matt Smith Is A Confused Puppy
Tennant was a man of action, and a man who, even whilst seemingly running around with absolutely no idea what he was doing, he had a plan, and everything was under control. He was a genius, and could turn any situation around. Smith is like a puppy that jumps into the pool for the first time whilst chasing a ball, has no idea what is going on, and frantically starts paddling in the hope something works. Capaldi on the other hand, is a strong actor. He is the only man who can buy the TARDIS and stop the Doctor from taking it back (Fires of Pompeii). Capaldi, as Malcolm Tucker, is ruthless, brutal, and unstoppable. If he brings some of that into Doctor Who it would be incredible.