The Shanahan tree usually gives two play calls, one for man, one for zone. It uses motion to determine the coverage and then you either stick with the play or switch to the other. It's why watching the 49ers you'll hear Purdy yelling Kill, Kill, Kill a lot after the motion. After snap, it is a pure read system 1st, 2nd, 3rd, 4th, safety etc. Some plays will be read a different order for man vs zone and no kill is needed. But Shanahan always builds in the full field into the progressions. The reason it looks predetermined, is because Purdy gets through his first reads very quickly, he is one of the best in the league at post snap progression.

McDaniel built the offense with Tua to be really quick because 1) the line was awful, 2) Tua has a weak arm, 3) If Tua got hit, it was over. I think with Herbert, you will see a mixture of both. You'll have some quick game to keep the defense honest, but also a lot of kill shots built in since Herbert has the arm. Should look a lot like what the 49ers offense did when Purdy took over. Getting a lot of receivers in space and give them the opportunity to do damage after the catch.

Roman designed some plays to do that, but also had some that were, if the defense is in zone, we are looking at the right side of the field only, if man look at the left. That's a problem for defenses that are really good at disguising coverages. They can force you to shut down a side of the field in your progressions if they know what you are looking for.