I've thought a lot about this and have wondered what would be a good way to measure this. To me the best indicator of a player's talent is as a recruit who else offered the player and what options did the player have when they were being recruited. I have gone through the 2015, 2016, and 2017 rosters and counted the number of players who received at least one P5 conference offer during their recruitment. By my count, this number has increased quite a bit since Sitake has taken over although Bronco and staff are still responsible for at least part of the increase.
The off season is long, I made this list for fun and for my own curiosity. Its hard to know exactly who had what offers, and if they were actually legitimate offers, but I took a shot. These are the guys to the best of my knowledge had at least one P5 offer to go along with their BYU offer. This is not a perfect indicator of talent on the roster and there are a lot of variables but the number of players on the roster the last 3 seasons with at least one P5 offer is as follows.
2015- 26 players with a P5 offer
Chris Badger, Devon Blackmon, Squally Canada, Tyler Cook, Mike Davis, Taysom Hill, Troy Hinds, Adam Hine, Austin Hoyt, Scott Huntsman, Jacob Jimenez, Colby Jorgenson, Tuni Kanuch, Bronson Kaufusi, Nick Kurtz, Harvey Langi, Tanner Mangum, Ryker Matthews, Mitch Matthews, Tevita Mounga, Butch Pau'u, Graham Rowley, Talon Shumway, Leroy Sitake, Sione Takitaki, Fred Warner
2016- 33 players with a P5 offer
Chris Badger, Squally Canada, Austin Chambers, Mike Davis, Kavika Fonua, Taysom Hill, Troy Hinds, Austin Hoyt, Scott Huntsman, Tanner Jacobson, Jacob Jimenez, Tuni Kanuch, Isaiah Kaufusi, Nick Kurtz, Harvey Langi, Uriah Leiataua, Keifer Longson, Inoke Lotuleile, Tanner Mangum, Tevita Mounga, Butch Pau'u, Keenan Pili, Alema Piliami, Thomas Schoaf, Talon Shumway, Leroy Sitake, Sione Takitaki, Handsome Tanielu, Beau Tanner, Jonah Trinnaman, Fred Warner, Troy Warner, Jamaal Williams
2017-43 players with a P5 offer (counting those expected to be added for fall camp)
Matt Bushman, Squally Canada, Austin Chambers, Kavika Fonua, Bentley Hanshaw, Troy Hinds, Austin Hoyt, Scott Huntsman, Tanner Jacobson, Jacob Jimenez, Austin Kafentzis, Tuni Kanuch Isaiah Kaufusi, Austin Lee, Uriah Leiataua, Keifer Longson, Inoke Lotuleile, Tanner Mangum, Tevita Mounga, Butch Pau’u, Keanu Saleapaga, Thomas Schoaf, Talon Shumway, Leroy Sitake, Sione Takitaki, Handsome Tanielu, Beau Tanner, Wayne Kirby, Ula Tolutau, Jonah Trinnaman, Joe Tukuafu, Taipe Vaka, Fred Warner, Troy Warner, Kody Wilstead
Those not currently on the roster who will be added for 2017 fall camp: Chaz Ah You, Zo Fauatea, Langi Tuifua, Mika Tafua, D'lo Gunter, James Empey, Jeremiah Ieremia, Khyiris Tonga
Again not a perfect list or perfect indicator but In my opinion the talent and the quality of recruits on the roster is trending upward.