There is always debate about coaches with supreme talent....ie Phil Jackson and 70’s Chuck Noll. Coaching or players? My guess is both!
My experience is really good coaches make a huge difference. Great athletes with mediocre coaching will succeed, but with limits. Great athletes with great coaching succeed with much higher limits. Mediocre or poor coaching pull their athletes in that direction.
To me the attempt to belittle an extremely successful coach's coaching ability by labeling their succees as simply a product of their athletes is poor reasoning. In athletic endeavors in most cases we measure the athletic quality based upon wins and losses, successes and failures. Then for some there is a need to belittle others' successes and achievements by changing the measuring stick.
Chuck Noll was a great coach as was Tom Landry, Don Shula, Vince Lombardi, Bill Walsh.
Bear Bryant was a great coach, as was Tom Osborne, Dan Gable, JoePa, Gus DeAugustine, Donny Rohn or Dick Rhodes.
Bill Belichick is a great coach as is Cael. They all did it somewhat differently, but their end product has been a level of success way above average.