I've seen two BYU practices this yr and follow them quite a bit. I am a Utah fan but I track BYU every year and respect Kalani immensely. 

Offense

OL-I think the Y's OL is talented but will experience what Utah went through last year with inexperience. Utah sent 4 OL to the NFL and replaced them with highly touted recruits. The fanbase was eager to hype them and see them on the field. They were great at run blocking and struggled with pass protection. I see similarities with this yr's OL. They will be better with the run blocking schemes. They are talented but will struggle. Replacing the three interior linemen is such a difficult task. I expect these guys to be an OK unit but give up big sacks and have lots of early errors. 

RB- I think the OL can get a push, but there apparently isn't an RB1 option. I think RB will be what the WR was last yr (they'll struggle and have lots of self-inflicted wounds).

WR/TE- I lump these together because from what I've seen they are going to use the TE just as much. I think last yr was a colossal , but I think this group is starving and ready to bounce back. If the TE's can stay healthy, it will open up some space underneath for Collie. This group needs one X WR to step up. They need one guy outside to play at a B level. To be seen but I think they can do it. 

QBs- I think it's been debated on CB, but both guys have drawbacks. Tanner struggles with pressure and makes the strangest reads. Wilson has yet to take a snap. It's very different when you come out the gates with Zona. They won't be world beaters on D, but they'll play faster than they've seen and play for TOs. The team could have B+ grades on O but if you have poor QB play it doesn't matter. I really worry about these guys. They need to get hit and by all accounts aren't in practice. 

Defense

DL- I think this is unit has the most potential. Tonga is an NFL talent. DE is a big concern. Kaufusi needs to step up big time on 1st and 2nd down. If they don't get pass rush with 5 or 4 with Kalani's scheme, they'll be in trouble. I think this unit is similar to past BYU lines and you want to attack the edge. If they can figure out how to get a rush a protect the edge (looking at you Corbin), they'll significantly improve the secondaries lives. 

LB- I am happy that Kalani has learned from the Langi experiment and put Takitaki in his true position. I expect BYU to transition to 2 LBs when they play the P5s and 3 LBs vs. the lower caliber talent. This group will be more vital in lesser , but no less they need two reliable options. I think they have that with Butch and Takitaki but depth is scary IMO with this unit. If they stay healthy, they can help this team get to a bowl. 

Saftey- This group has a potential NFL talent in Ghanwoloku if he can stay at safety. He struggles in man coverage but is an excellent tackler. I think the move provides him space and suits his skills better. This unit isn't deep but could make a name for itself, like the OL I think they are a yr away. 

CB- I think this is the weakest unit on the team. My guess is they move the safety talent back to CB out of need. They got burned last yr and tackled so poorly outside of Ghanwoloku. I think if there is a team with a decent QB they'll pick apart this unit. 

Overall- I think the Y will have its moments, but the mistakes and inexperience will catch up. I expect Byu to sneak out a win vs. Cal but lose a head scratcher to NIU or USU. I think Byu is a 6-6 team. Utah went 5-7 two years in a row. The schedule was tough, and they had poor team speed and lacked a QB. I think if you give Kalani time you'll see these two down years will lead to greater things going forward. He is handcuffed with the HC, but I think there's enough LDS talent to turn BYU into a top 40 team annually.