One of his 6 years was a redshirt. He was finished in 2019 before COVID so that does not factor in. It does show 5 years of wrestling though. The only thing I can think of is that maybe he got a medical year it's not showing. Liberty is a D1 school, but wrestling was downgraded to club status in 2011 or 2012. So I am not sure if there are stipulations with the school being D1 but the program being club NWCA. Also, I am not sure if 2015 rules were different than today.
https://www.wrestlestat.com/wrestler/40240/diehl-ryan/profile