I do believe it. I am close to a chiropractor who worked with NFL team for 10 years. He tells me stories all the time. In fact, after all that time, he told one physio he didnt know what he was doing, and was fired on the spot.
There isn’t a cause and effect between S&C and injury history or S&C and teams performance. It’s an entire organization approach as you could have different scenarios of the owner, coach, physio, S&C all playing a role that could negatively impact a player/team.
Maybe many of these injuries have re-occurred because of their high salaries, that the owners demanded they play and over rode the phyio and team Dr’s advice??? We don’t know the entire story, but what is known in most cases is that a player(s) misses a game(s).