3 of the 5 NFL draft picks last year were from offense, and the two that were defensive players were in the last round. Not to mention replacing Zach Wilson, who was far more important than anyone the defense lost.
It’s not like the offense didn’t have its share of injuries. Jaren Hall struggled with injuries almost the whole season. Even when he wasn’t forced to miss games (like USU or UAB) he was clearly hobbled in others. Multiple offensive linemen, Mason Wake, Isaac Rex, WRs… Oh, and replacing both the OC and OL coach. Yet the offense ranked out well above average statistically, and much better than the defense.