I saw Chris Hassel thinks 2015:
I say 2019. Hawks were 10-3, ranked 15 in the final AP poll. Lost 3 one-score games to ranked opponents:
3-10 @ #19 Mich
12-17 vs. #10 PSU
22-24 @ #16 Wisconsin
Ranked wins against #7 Minnesota and #22 USC.
BCF Toys FEI rankings had us as #18, with the #53 offense, #12 defense, and #3 special teams.
24 guys from that roster at least sniffed the NFL (not all were contributors during that season, of course): https://www.sports-reference.com/cfb/schools/iowa/2019-roster.html
I say 2019. Hawks were 10-3, ranked 15 in the final AP poll. Lost 3 one-score games to ranked opponents:
3-10 @ #19 Mich
12-17 vs. #10 PSU
22-24 @ #16 Wisconsin
Ranked wins against #7 Minnesota and #22 USC.
BCF Toys FEI rankings had us as #18, with the #53 offense, #12 defense, and #3 special teams.
24 guys from that roster at least sniffed the NFL (not all were contributors during that season, of course): https://www.sports-reference.com/cfb/schools/iowa/2019-roster.html