QB:

At QB he had Taysom Hill, who was on his way to being a Heisman Candidate in 2014 and would likely have been again in 2015 if he hadn't been injured.

Behind Hill has returning starter and Freshman All American Tanner Mangum.  A potential heisman candidate and Freshman All-American.  Honestly, that was one of the best QB situation in the Country.  Injuries (both physical and emotional/mental) prevented the realization of that talent in future years, but at the end of 2015, it was a situationany school would envy.

RB:

1) Jamaal Williams.  No further comment needed.

2) Algie Brown.  Algie averaged 5.6 ypc.  In his 7 starts, he scored 13TDs (11 rushing, 2 receiving).   For comparison, in 2019, all of BYU's RB combined scored 13 TDs (12 rushing, 1 receiving).

3) Francis Bernard was a very impressive RB his freshman year.  He averaged  6.4 yards per carry and had 7 rushing TDs.  He also also had 17 receptions for 156 yards and 2 more TDs.  This guy had multiple 1000 yard seasons ahead of him.  However, Kalani moved him to defense (where he was also very good) and then he left the program.

4) Squally Canada.  A P5 transfer with a lot of potential.  We saw what he could do when healthy at the end of 2017 and the beginning of 2018.  As further testimony to how impressed Kalani and his coaches were  with Canada, they moved 2 of the guys ahead of him on the depth chart (Algie and Francis) to different positions.

The RB situation Kalani inherited was one of the best in BYU history.  You have Jamaal Williams.  You have another returning starter in Algie, who despite starting only 7 games, still accumulated over 700 rushing yards and 13 total TDs.  You have Francis Bernard, who looked like he would be the next great Cougar RB, and then Squally Canada.

In summary, Bronco left the RB and QB pantries absolutely stocked.  However, what Bronco left and Kalani put on the field were not the same thing.  Due to position changes and other issues (some of which the coaches were responsibile for, others were beyond their control), that incredible wealth of offensive talent did not translate into incredible offensive play.