If you use that logic, our win against the highest ranked opponent, MSU, is no longer impressive since they’re now unranked.
Your argument is centered around we haven’t lost to many bad teams, which is fine and all, but not how most people, especially AP voters, vote for top 25. The saying to be the best you gotta beat the best applies here. TTU’s signature wins were against the #1 team on the road and also beating the #6 Jayhawks. Again, they have 7 wins against ranked team in total. Our signature win was against a previously ranked #10 MSU at home that we won by 1, which according to the same logic you applied isn’t impressive given MSU is now unranked. And we only have 4 wins against ranked teams (2 if you exclude wins against MSU). That what the voters see when they’re submitting their votes.