Yes coached up. Thats why he sat the bench his rookie year. Said directly out of the player mouth
Just in preparation, the mental side of the game, I definitely benefited,” Mahomes said. “Being able to watch how teams made adjustments, and then how we made adjustments to the defense, how we’d figure out what blitzes they were bringing, how to protect them, it definitely helped me in the game [against the Chargers]. It’s knowing how to operate the huddle, and then being able to go out there and execute the game plan how it’s supposed to be run.”
Playing the scout-team quarterback in practice really helped develop my game. When we were playing the Jets, with Josh McCown, I'd have to throw a lot of deep balls. Tyrod Taylor with the Bills, you'd have to scramble around a lot. With Tom Brady, it was about dissecting the defense. You go through other offenses, and you make them into your own, and try to make it relate to your offense. I had to do stuff I wasn’t comfortable with, and see what I liked and what I didn’t like.