Mid-majors ranked in top 25 nationally with very similar experience: Belmont starts FR,2sophs,JR, and SR. Buffalo: 2JR,soph,FR,SR. Very quick research, I am sure their are more examples of both very experienced and very in-experienced successful mid-major teams.
There are sites out there that do this work for you. Based on minutes distribution by class, Lehigh was the 68th youngest team in the country (if you based it on statistical production Lehigh would probably skew even younger as CS played solid minutes without a lot of statistical contribution). By contrast, Buffalo was 198 (older than average). Belmont is a good example as they were the 105th youngest, although significantly older than Lehigh. There were two teams in the PL this year younger than Lehigh (BU and Loyola) both of which finished under .500 overall. The three most experienced teams (Colgate, American, and Lafayette) all made the conference semis.
The top 5 of the mid major top 25:
Gonzaga (307th youngest of 351)
Northern Iowa (318th youngest)
Wichita St (190th youngest)
Stephen F Austin (214th youngest)
Murray St (294th youngest)
This team absolutely has a ways to go, and very well may never get there. There were certainly times this year where there was no cohesion, uncertain roles, and ugly play. There were also times when they played very, very well. I don’t think you can discount experience (and adjusting to roles) when looking back on this year, or forward to next year.