I'm skeptical the talent gap is growing.

It seems to me that 247's yearly team talent composite ranking is a better measure of overall talent than the recruiting ranking 4-year rolling average, as the composite ranking reflects the actual players on the roster rather than those that were merely committed once upon a time. 

BYU's and Utah's composite rankings for 2015-2018 are below (the 2019 ranking has not yet been posted):

BYU: 63, 61, 52, 55

Utah: 50, 51, 39, 44

For context, the 2018 talent composite rankings gap between Utah and the class of the PAC12 (gap with USC, 40; gap with Stanford, 26; gap with UCLA, 25; gap with Washington, 24; gap with Orego 19) is far greater than the gap between Utah and BYU (11), and the gap does not appear to be growing.