Can't force someone to train hard, as a trainer you can only go so far. Provide a proper program, nutrition, and guidelines...at the end of the day its ultimately up to the Athlete.
People don't realize that S&C Coaches have the guys for maybe a collective time of 16 weeks each year of an actual weightlifting program. You have Spring which can be maybe 4-6 weeks TOTAL because you have to also practice on a football field. The offseason may only be 12 weeks collectively, now imagine the type of training program that has to be implemented. You have technique if olympic lifts are incorporated and even deload weeks incorporated.
The specific Athletes motivation to continue the process on their off time is solely up to them. I genuinely think people don't realize the little amount the S&C coaches actually have with the team in terms of a strength training protocol. 4 months a year dedicated to getting stronger and building muscle is nothing, the rest of the year is up to them individually and then of course you have the variables in how much they actually care in the given time with the coaches.
That's why Ed in all of his interviews emphasizes the important of "Culture", when he was a player here they were self motivated and that has been lacking in the program for a very long time. I also think the "Culture" can shift with results on the field. Losing teams have poor motivation because they have been losing for so long and we have been losing for a very long time. That's what Manny is trying to change, it all starts with winning in the actual games and then it translates. Anyone who has played sports knows that the nucleus of a program/team is the players themselves and when you see results on the field translating to wins, that translates to "Culture".
TLDR .. Players need to actually give a f***