Build columns from the expected dropback model. Will return NA on data prior to 2006 since that was before NFL started marking scrambles. Must be run on a dataframe that has already had clean_pbp() run on it. Note that the functions build_nflfastR_pbp() and the database function update_db() already include this function.

add_xpass(pbp, ...)



is a Data frame of play-by-play data scraped using fast_scraper().


Additional arguments passed to a message function (for internal use).


The input Data Frame of the parameter pbp with the following columns added:


Probability of dropback scaled from 0 to 1.


Dropback percent over expected on a given play scaled from 0 to 100.