This is a really good article on the NFL's offensive coaching trees.
What are the secrets to coaching lineages that include Sean McVay and Kyle Shanahan, and Andy Reid and Doug Pederson?
www.theringer.com
I would also add the Schottenheimer/Arians tree. That is what we saw this year. It generally consists of long dropbacks, shotgun, and 11 and 0 offensive formations.
The Reid tree is interesting. Those coaches use lots of RPOs, shotgun passing, and speed to attack defenses. The running game and play-action are somewhat less important than in...
The Gruden/Shanahan tree. This is the west coast, zone blocking, and play-action heavy offense. This is what Stefanski is part of and what we will see this year. My eyes tell me that Stefanski is closer to Shanahan than McVay. McVay likes speed and tends to avoid heavy formations whereas Shanahan likes heavy formations to confuse defenses while keeping the offense incredibly simple for the quarterback. This offense does require the quarterback, offensive linemen, and runningback to make reads on every play. But, if they are coached and able to do so, it is unstoppable in the hands of a good play-caller.
I think the Arians tree is dying. It is easier to defend and, as analytics on efficient passing plays continue to emerge, it is clear that this offense requires very specific players. I was ecstatic about bringing in Monken because I thought he would bring formation strategies that make this offense more efficient at the college level. Regardless if he did and Freddie just ignored it, those concepts were never adopted, and we ran some weird Arians-style offense that was ineffective.
The Reid and Shanahan trees are taking the league by storm. All four playoff teams use one of these offensive systems, and if you are not paying close attention, they look similar. Their main goal is to empower the quarterback and confuse the defense - they just do those things in different ways.