I think the thing we will miss most if we lose C.J. is his 1st quarter scoring. I have not run the numbers for the 2017-18 season, but when there was talk of trading C.J. late in the 2016-17 season, I did and C.J. was both our most prolific and most efficient 1st quarter scorer. If Lillard Time is the last 5 minutes of the game, the first 12 minutes are McCollum time.
Why is that important? Again this data is from the 2016-17 season so it may have changed a little, but we were a horrible 1st quarter team constantly falling behind by double digits in the first quarter, only to spend the next three quarter trying to claw our way back into the game. Sometimes that works, sometimes it doesn't, but it always requires expending a lot of energy, which wears players down, both physically and mentally over the course of an 82 game schedule. Removing our best 1st quarter scorer would have made that bad situation even worse (which is why I have never advocated bringing C.J. off the bench).
I'm all for trading him for someone like Butler, a better overall player, but don't just assume one of the young guys (or cheap 1-year contract vets) will be able to step in and immediately replace what C.J. gives us. I think Simons has the greater long term potential, but I think Trent has the aggressive attitude and self-confidence to step into the rotation sooner.
BNM