If Marinelli isn't good at his job it's because of the style of defense and teaching methods, which is entirely different from hard work. Passion Nobody ever questions Marinelli's effort and passion.
If Taco was unwilling to give his best effort because he didn't like the system, that doesn't in any way justify him not giving his best effort. Lawrence still gives his effort. Crawford, Collins, Woods and on and on ….
The world doesn't work where the employees get to dictate to management how to run the company, and in any business if a person refuses to give a strong effort because they don't care for how management runs things, they lose their job. That's not just an NFL thing.