I think it doesn't really enter the equation. The single worst lecturer I've had at university is now a professor. I don't enough about tenure tracks and we also call them differently (not adjunct, associate, etc) - but he's still there, 20y later, teaching (I think he just had gotten his PhD back then). I can only hope he has improved from "open script, read one page at a time, close script, dismiss".
Meh, not actively messing up the course is already better than some of the other professors...
At least he showed up! That is what we call an A for effort.