I agree with Nessy. The Doctor is meant to be a bit silly, young at heart, good with one liners and a sense of fun for the kids, Ayoade would seem perfect for that part. However the lightness, the comedy is meant to be balanced out by the sense of a man who has lived for so long, seen a lot of tragedy and had a lot of loss, who sometimes takes hard decisions, the big dramatic speeches, will have a big regeneration scene. No idea if Ayoade can supply that part.