Notre Dame’s running backs and quarterbacks have been on opposite sides of the transitional cycle natural to college football. While the Irish had confidence, certainty and stability returning in 2020 with Ian Book leading the offense, they had no idea who would supplement him in the backfield.

Now Book is training for the NFL draft and the quarterback room is filled with questions and vague answers as Notre Dame’s offense will instead focus and feature Kyren Williams and Chris Tyree.

Maybe the outside presumption was the Irish would highlight Jafar Armstrong in 2020, the receiver-turned-running back having shined early in 2018 and clearly a playmaker when at his best. But that outside presumption had no idea the damage seemingly done by Armstrong’s torn abdomen in 2019.

Admittedly, not seeing any spring or preseason practices limited that insight, but logic should have also recognized its possibility. A running back relying on agility and speed will be greatly impaired by tearing his core muscles.

And then Irish head coach Brian Kelly listed Armstrong fifth when discussing running backs two weeks before Notre Dame’s 2020 opener. That was not a literal depth chart, but Kelly’s stream of consciousness ended up looking much like 2020’s usage order. And at the top of both …

“Kyren Williams has really emerged as somebody that we feel right now has gained an advantage as the top back right now,” Kelly said on Sept. 1. “He’s going to require some assistance at that position from a number of other guys, we’re not going to feature just one back, but Kyren has done a great job.”