This is from KenPom, his non-conference SOS rank:
2010: 147
2011: 46
2012: 114
2013: 65
2014: 9
2015: 22
2016: 89
2017: 211
Obviously you can't predict how teams you will schedule will play and that will determine how these rankings turn out, and it's also impossible to say the teams on 2018's schedule won't all be super good and up this ranking considerably, but up till last year BYU's strength of schedule had been in an acceptable range. Here's to hoping next year's ends up much higher than last year's.