That seems like forever ago. It's hard to believe how much this program has changed since 2013.
According to Sports Reference, the 2013 Nebraska team had 27 guys with a hyperlink to their NFL stats. Out of boredom and curiosity, I went through and looked at the 2013-2019 teams to find the number of guys each team had that had a cup of coffee in the NFL. (Adding DPE and Zach Sterup who didn't have links to their NFL pages despite having signed NFL contracts, but otherwise counting players strictly based on if they had a hyperlink to their NFL stats. RS years are counted and the player counts for every year he was on the roster.):
2013: 27
2014: 22
2015: 24
2016: 18
2017: 12
2018: 8
2019: 5 (Davis, Davis, Daniels, and Jackson....and, oddly, Mo Barry)
A lot of the guys with NFL mentions never amounted to anything in the League, but in terms of talent, that 2013 team was absolutely stacked versus what we're dealing with today. The 27 guys with NFL hyperlinks doesn't include rock-solid college only players on the team like T-Magic and Sam Foltz, either.
Regardless, I think Nebraska will be back in the 25-30 range on an annual basis fairly quickly and the numbers for the last couple of years will increase as guys continue to graduate or go pro and with the inevitable practice squad opportunities that a guy with an NFL body like Alex Davis might be able to find.
For comparison, 2019 LSU has 17 players already hyperlinked and that number will go way up in the next couple of years. I also looked at the 2016 aOSU roster because it was Urban Meyer's 5th year there, so it was his first year with a team made up of all his guys, and they had an impressive 34 players on that roster with NFL mentions.
https://www.sports-reference.com/cfb/schools/nebraska/2013-roster.html
The site puts little "NFL" badges next to some NFL players, but a guy who was drafted, Tanner Lee, doesn't have a badge and a guy who played in regular season games last year, Stanley Morgan Jr., doesn't either, so I really don't understand their methodology.