The Chiefs and Bills have similar run and RPO schemes. It's pretty easy to see why Daboll Hired Kafka. Great minds think alike.
Andy Reid was the first coach in the NFL to incorporate heavy use of RPOs. Reid's stated goal was to merge short game concepts from the West Coast Offense with the college RPO game. It's pretty safe to say that it's been successful.
In breaking down the Chiefs and Bills shotgun run games it's probably easiest to break up the run and RPO pass concepts. Both teams will pair multiple pass concepts with each run concept.
The Bills also made heavy use of designed QB runs known as "Bash" - or "back away" concepts, and these plays were explosive.
RPO Passing Concepts
Most of the RPO concepts used by the Chiefs and the Bills attack the inside LB to the side of the RB.The offensive line doesn't block the LB, and he is the QB's "option" read. After the ball is snapped, the QB puts the ball in the RB's belly while eyeballing the LB (S) in the diagram below. If the LB flows with the RB, the QB pulls the ball and reads the flat defender ($) who is in a major bind having to defend the flat and the slant. If the LB honors the slant, the QB gives the ball to the RB, and the offensive line is blocking 5 vs 5, which the offense should win.
For both the Bills and the Chiefs, RPOs were first and second down calls.
These types of RPOs can be run with 1, 2 or 3 receivers to the side of the RB, but there is always 1 receiver that is running into the LB's zone.
Double Slant Flat
Stick has the inside receiver attacking the LB
If Daboll and Kafka want to throw downfield, they can call the skinny post, also known as a "Bang 8" or "Glance" route. This is the pass that epitomizes the Troy Aikman to Michael Irvin connection from the Cowboys glory years. Fake to Emmitt Smith and drill the ball to Irvin. This works best with a big-body receiver. The skinny post should be a Kenny Golladay staple.
RPOs can also be run from many formations and motions. There are some plays where a WR motions into the backfield, and the outside receivers block for the WR on the swing pass.
RPO Run Concepts
The passing concepts above can be paired with a wide variety of run concepts.
Pin & Pull
The pullers change based on the front. The Chiefs and Bills will sometimes pull the center.
The linemen are blocking areas and trying to drive the defense to the sideline.
Counter is the old Washington "Counter Trey" which pulls the backside guard and tackle.
All of the runs from under center (Section 4 of this series) are run from the shotgun as pure runs as well. They Include Inside zone, Outside Zone, Middle Zone, Pin & Pull, Fly Sweep, and Counter.
The Chiefs didn't do much in the way of designed QB runs - Mahomes isn't built for it. The Bills, on the other hand had a robust QB run game. The first is Zone Read, where the edge isn't blocked, and the QB reads him for handoff/keep. Using the H back or TE as a lead blocker is sometimes called.
This is where the Bills's run game gets intriguing. "Bash" is short for "Back Away". Bash has the RB and QB exchanging responsibilities in the running game. They still line up in the same positions, and the QB still receives the snap, but the blocking scheme is executed opposite of where the RB is headed and the QB keeps the ball. The Bills did this with all of their shotgun runs. By my estimate, Josh Allen had 3-5 designed runs per game, and they were extremely successful. There were several plays where Allen had clean runs into the secondary.
This could be a big winner for Daniel Jones if he can learn how to slide.
At the college level, the QB can read the DE for handoff/keep, but the Bills did not appear to be reading Bash.
Bash plays are relatively "cheap" for Kafka and Daboll to install. The blocking and ball handling don't change a bit. If the defense is keying hard on Barkley, Jones could find plenty of open grass.
Inside Zone Bash
The QB follows the pulling Guard and Tackle