McCollum is really underrated. I've seen him have some monster games playing the PG whenever Lillard has been out. Besides, I'm really confused as to why he can't play PG. Can he handle the ball? Yes. Can he execute the PNR? Absolutely. Is he at least an average passer. Yes. Is he a pure PG? No. However, how many players in today's NBA are really pure PG's? The league is riddled with score first PG's like Westbrook, Lillard, Curry, Irving, etc., so the notion that McCollum will be unable to play the position seems shortsighted.
I do think Irving is the better player, but if we were able to work out a 3 team deal where we would receive McCollum and the Blazers 1st rd pick this year (I think that'll be a late lottery pick with them getting squeezed out of the playoffs), then that's something I'd really consider. Especially with the uncertainty of Irving's pending free agency.
Statistical comparison over the last 3 seasons (since CJ has started)
McCollum
Games Played 80 - 81 -80
PPG 20.8 - 23.0 - 21.4
APG 4.2 - 3.6 -3.4
RPG 3.2 - 3.6 - 4.0
FG% 44.8 - 48.0 - 44.3
FT% 82.7 - 91.2 - 83.6
3PT% 41.7 - 42.1 - 39.7
Irving
Games Played 53 -72 -60
PPG 19.6 - 25.2 - 24.4
APG 4.7 - 5.8 - 5.1
RPG 3.0 - 3.2 - 3.8
FG% 44.8 - 47.3 - 49.1
FT% 88.5 - 90.5 - 88.9
3PT% 32.1 - 40.1 - 40.8