Yes, he was theatrical, but I believe he was trying to play all the Doctors in his regeneration. I think I heard that somewhere.
Behind his eyes was a madness as the asylum in his head was full of lunatics who always managed to save the galaxy.
It was great acting, with poor costumes, special effects and writing.
Hartnell was overly theatrical, as was Baker at times.
Baker was a clown, like McCoy, but Baker knew when get serious, when the plot dictated it, whereas McCoy never really knew how to adjust to that.
The world is about to end and you can't keep acting like a John Steed when you are a badly dressed Joe Pesci.
Take for instance, Tom Baker in "Seeds of Doom." I watched that last night.
When everything got serious and Cordy was ready to throw the Doctor out to the giant plant monster, Baker would explode at him after spending three episodes belittling him.
That's acting!