My definition of the term is completely correct. And the report states it was his back that was atrophied. No reason for that at all. a broken foot will not effect working on your back.
You're wrong.
He's not though. Hayward has been weight bearing since the middle of last season. Nothing was stopping him from working on his core or doing trunk extensions.
Core exercises and trunk extensions are not even close to the same thing as playing full-court, full-contact basketball... let alone professional basketball game after game for months. I’ve always noticed the my back is the most sore after I go for awhile without playing full-court hoops. But I run year-round and work on all muscle groups at the gym. Functional, specific strength isn’t something you can isolate well in the gym. Not to mention your foot is part of the kinetic chain and everything affects everything else. Etc.
This would all be a good point if they didn't specifically say in the article the muscles in his back had actually atrophied. This is something that happens to teenagers who sit around all day playing fortnight, not world class athletes with every resource in the world available to them during the rehabilitation process.
Hayward is a guy who got paid and stopped being hungry. It happens. He now shows upto work when he wants to (and only when he wants to). He's not terrible - his per 36 numbers this season are all in line with his career numbers.
But he's never going to be the guy everyone wants him to be... He wasn't even that guy in Utah. The Celtics will most likely move on from him this offseason (if they can find a taker).
Yes, the muscles atrophied after... however many months of sitting in a chair and being unable to exercise in ways that would allow him to maintain peak fitness. There are not a lot of exercises you can do for your back that don't require a base of lower body stability, and that actually make a difference in terms of dynamic, functional strength... i.e., once again, lying on your belly and doing lower back extensions are not going to make a $%#&ing difference in terms of fullcourt, fast-paced, contact basketball. It just won't do it.
I really, really doubt he's making the calls about "when he shows up to work." That's on coaching staff and trainers.
Not sure what your last point is, that he wasn't even that guy in Utah - what's that, not an all-star, not borderline all-NBA? 24/6/3 in the playoffs?
But, fine, be hardheaded about how muscles work and what a lifelong top-tier athlete's motivation and work ethic is like.