I think Ingles also tries hard, but he has limited skills. Favors and Gobert are solid. Hayward takes losing hard, hangs his head, and then quits. Look at the D he played against LBJ. That was amazing! And Booker can bring attitude, but has tailed off. It's a downward spiral right now. I've been there on an amateur level...you just don't invest as much effort once the losing starts. The motivation isn't the same. Sure these guys are getting paid to play, but there's a completely different attitude when you're playing to win, vs. knowing that each game is likely going to be a loss.
To a certain extent, I think this is also what happens to Trey. He's "clutch" in the last 5 minutes if the Jazz are close. The concentration is better; the effort more intense. He just can't/won't do it for the first 43 mins. I just wish Exum were more polished so Trey would have a true threat behind him, ready to take away the starting job.
I don't think Favors tries hard on D. He's naturally a pretty good defender, and he likes to block shots. But he doesn't play with any kind of intensity on either end. And Favors is my favorite player on the team, so I'm not just bagging on him. Gobert is great defensively. But I agree about indifference due to lack of urgency.