Evaluating an offensive coordinator can be a difficult task. Stats, rankings, and advanced metrics are all heavily influenced by the performance of the players on the field. Bill Walsh could've been the New York Jets' offensive coordinator during the Zach Wilson years, and the offense still would've been a bottom-ranked unit.
On the flipside, Peyton Manning's excellence made folks think that Adam Gase was an offensive genius. We all know how that turned out.
Watching the film can help us glean how much of an offense's struggles are on the players versus how much responsibility should fall on the play caller's shoulders.