Even past COVID year eligibility, college teams are getting older and older due to various redshirt grants, transfer portal and more "academic hold backs" (ie, a 20 year old senior in high school)
BYU used to be unique in having 23-26 year olds on the team due to mission work. And arguably, people would say that BYU would have an advantage as at 23-26, your body is more developed than an 18 year old.
But now, teams have older players in general. I don't think the talent has declined. What has declined are the variables on "potential".
Before, you would draft a kid that is let's say 20 years old in college whose body is not fully built but has potential. Now you are drafting 24 year old guys like Fiske and 23 year old guys like Verse. They are big boy bodies playing in college. So you have what you have. If you are 24 years old on the D Line and can't dominate an 18 year old OL, then you are not going to have high potential as your upside on body build won't be higher compared to the 18 year old.
And then with all the testing, social media access etc... these guys are more known commodities than before.
So I think the perception has changed which may make it seem like there is talent dilution, but there may not be a difference.. just the comps are different.