They didn't bother with Colin and Sylvester's faces because let's face it after Davison they gave the job to any old fucker with an Equity Card. (c) Mark Gatiss 1999
I feel bad because I love Colin & Sylvester but I still think this is funny.
And while it's not the fault of the actors, I do think there was sort of a haphazard mindset behind the casting during the JNT era. It seemed like the mindset was less about finding the best actor and more about deliberately finding actors who contrasted with their predecessors. Even Davison was, IMO, a somewhat dubious choice. He's a good enough actor that he was able to fake his way through it but I don't think he was really Doctor material, certainly not back then. (He's kind of grown into it while doing the audios. As an older man, he'd acquired a certain deadpan, Pertwee-esque charm to go alongside his youthful earnestness.)