I've been critical of this year's defense and have blamed it for the losses this season. I stand by that. The defense is the obvious weak link on this team. That being said, I do not believe that this year's offense is as good, or better than last year's. I think they're good...and capable...and would be 7-1 or 6-2 with an average defense.
My opinion is that if you took this year's defense and replaced last year's with it, that team would have likely lost the Utah, Stanford, Cal and Iowa State games that were so, so close. If that happens, that team is then a 7-6 team, instead of an 11-2 team. Well, they wouldn't even have played Iowa State because they wouldn't have been in the Alamo Bowl, so just regular season they'd be a 7-5 team. I seriously think they lose those games with this year's defense.
If you replace this year's defense with last year's on the 2019 team, the only game this team loses is the Utah game. They're sitting at 7-1 right now.
It's hard for me to have a feeling about how last year's team would have played with this year's offense, or this year's team with last year's offense. Beyond the intangibles like leadership, killer instinct, etc. that you can't measure, one HUGE statistic that is missing when comparing the offenses is TURNOVERS. I don't know what the differences are, but I have a strong suspicion that last year's offense committed fewer turnovers through 13 games than this year's has through 8. No turnover is a good turnover, but some of the turnovers this season (a lot of the turnovers this season) have taken points off the board and others have put the other team in immediate scoring position.
If I had to guess, I would say last year's team with this year's offense is a 9-3 team (bowl game not included). They probably drop one of the games mentioned above. This year's team with last year's offense is probably still sitting at 5-3. Our defense is just a wet paper sack.