I will say, Harbaugh is a good coach to have a quarterback develop under, and McCarthy operates very well within structure.
I think he could be competent right out of the gate, but you really have to wonder what the ceiling on him is with a lack of raw arm talent. Do you want to take the risk on that profile with a significant pick? Can he take you to a Super Bowl?
I think McCarthy ends up anywhere from middling starter to top-tier backup. There's upside depending on where he goes. Had Purdy not become a skilled operator of that 49ers offense, I'd peg him as a great fit there. The Rams also make a lot of sense.
If I had to make a guess now, I'd say Rams in the second round. Maybe Patriots.