Before I get started with my guesses, I want to state a few truths.
1.  I have no inside knowledge and have never personally met anyone in athletic department.. in fact I don’t think I ever met any of the coaches or AD back when I was at school in the 80s/90s.  Strictly a fan and hoops junkie.
2.  I have only ever posted as PKGW on this or any other GW hoops site.

After watching 2 years of JC and closing my eyes during the pre-conference struggles, here is a guess.

1.  He uses the pre-conf games to
Mix and match his rotations and see what works best without “real” worry about wins and losses to prepare his team for conference play.  He would rather win, but likes to see what rotations and combinations work.  Now I happen to disagree with this approach since you will
Never get an at large bid with this type of strategy (it may work at lower levels of D-1 since you would never get that bid) and maybe he changes this strategy when we get a team that may be able to compete for that bid.  In fact he will have to change that strategy to be successful at GW

2. After having watched his team though the pre-conference games , he sits down with each player and lets them know what their role will be goiing forward barring injury.  Some may call this running off but if this is the case, I actually admire his honesty.  I think we saw with Mazzula last year (maybe  told he would be coming off the bench 3rd as Point) and with Jameer And Maceo this year- the players are told where they will fit in the rotation.  While I respect the honesty it does hurt the team
Since injuries and poor play could change things and now you have less options.
Bishop and JNJ were never a good fit to play together.  Both like the ball in their hands and drive to the basket.  Both have turnover issues and realistically one was going to have to come off the bench.
Maceo was probably told he would be coming off bench behind Ball and Sloan.  For his future career, probably a great move to get playing time elsewhere to showcase his skill set.

Not sure this is accurate since I can not read minds, but just trying to put some logic into 2 years of horrible starts and departure of good kids.