Excellent questions. Were I to get a sit-down interview with David Lee, these are the ones I would ask him, at least as it relates to Jovan.
For the record, my money is on the tactical adjustment option. Lee may have had the vision of very pacey, adept wingers doing the pressing and disrupting with Jovan as the linchpin at the center, while Nick may have been fully committed to the CFG Way. Which would explain Jovan falling down a bottomless well late in the year.
But we won't know unless somebody asks.
Unfortunately, very few people outside of the team get that level of access and the ones that do like Crooks don't ask tough questions like that.
Going with the tactical adjustment option there is also the possibility that Cushing and Lee were aligned with that approach and then everything went out the window when Jovan showed up out of shape. We have a reasonable amount of evidence on that front. Jovan himself claimed he was only at 60% a few weeks into the season. We have the reports in here that someone on the forums that NYCFC brass was grumbling about his lack of conditioning and from his appearances his fitness only seemed to get worse as the season went on. Hard to blame Cushing for not wanting to adjust the whole team around a guy who couldn't even bother to be in shape to play.