OEP, also known as FEP, was created by Joe Sydlowski and Tan Ho and published in their
ffopportunity R package.
OEP quantifies the expected point value of each opportunity a running back receives on a play, independent of the play’s outcome. In the NFL, much of a running back’s value derives from the types of opportunities he’s given.
You can read more about OEP on 538.
How can I download the model input data?
The input data is free and open source and can be downloaded using the
nflreadr package.