sometimes it's the produce[r's,rs'] not catching on to what makes dr who; sometimes it's their not realising what drives him; occasionally it's been a thoroughly inappropriate actor getting tagged as the new doctor (and sometimes one such has suddenly woken up to the incredible opportunity he's been granted, and "picked up the ball and run with it" so far, so fast & so successfully, it's worked out very well indeed, after all: and some hitherto unknown and totally unexpected new facet of the doctor has been revealed.. ..of which, later on, further doctors've been able to take advantage)...