100% it’s a favor to Randal El to develop his coaching chops for inside Halas Hall and outside
This isn't a just a favor to help build a resume.
1)Johnson wants his assistants to see what he sees and can gather that experience to better work with the unit(s) that he coaches during the season.
2)He can call plays where he might want to see certain guys get a set amount of plays in their direction to see what they can do. The Bears have a logjam at the receiver spot and it's possible that there's a roster spot on the line. He needs to provide recommendations and you can't do that without seeing what you need to see.
3)MOST IMPORTANTLY, it gives Johnson a chance to sit back and see the game and his guys from a 50,000 feet view. You can't do that with your nose in a playbook managing the offense. He needs to do his own evaluations and take his own notes and see guys in various situations on both sides of the ball.
Part of the problem with being the head coach AND calling plays is that you're way too deep into the weeds to make individual judgements, thus, the standard....."I have to look at the tape" response. By handing the play calling off.....he sees the tape real time.
You have to remember, it's the preseason for everyone, including the coaches. They have a lot of very, very difficult decisions to make, especially given the injuries in camp. Handing over the play calling duties was not just doing ARE a solid. At the end of the day, if the Bears go 4-13 and the offense is significantly flawed, nobody is going anywhere except under a microscope. If the WR corp struggles, that would be a bigger issue.
There is a lot to work out and not a lot of time to do it.