Agree that Kofi can make a big difference. But, it's possible that a transfer power forward might be even more key for us than Kofi, because I think GB might be strongest for us as a 5 next year.
On defense, I tend to think sophomore GB will be better at the 5 than whatever-weight freshman Kofi we get. GB will be better away from the basket on the other 5, certainly in transition, and maybe even at rim protection (GB was coming on in his blocks at YE, especially help/backside blocks). And, if we have an actual power forward on the floor, I think our defense at 5, whomever is there, will be better - think we would have seen more rim protection from GB if he had less responsibility for supporting an undersized 4.
Remembering "the cone drill" video, I think GB can do a bit of slashing from the outside, if given opportunity, but if he's going to play 4 on offense, then we still need to see his 3pt shot kick in. I'm thinking/hoping he'll be OK as an occasional 3pt shooter next year, if he really works at it, but GB is just so good around the rim on offense (with that Nerf ball he uses), I have a hard time imagining anyone on our team producing in the post the way a sophomore GB should. If GB moves out of the post to the 4 to make room for Kofi, I see us "gaining ground" at the 4 (with GB instead of AG/Kipper), but losing ground on the net difference between GB and Kofi at 5.
Weakness at the 4 was so significant for us this year. I really have my fingers crossed (not predicting/just really hoping) that we get an upperclassman 4 to transfer in and start next year. If that happens, we should get defensive and offensive production at the 4 equal to (maybe better than) what GB might do out there, leaving GB to start at the 5 and give us more than Kofi (or January or Kane).
At this point I'm seeing a grad transfer having a bigger immediate impact at 4 than freshman Kofi at 5. Maybe that shifts, if Kofi really comes on as the year progresses. I know in some ways who starts "doesn't matter," but if we look to put the strongest five on the floor at the same time, then Kofi might not be one of them. If pressure (5* expectations) or confidence boosting dictates that Kofi starts next year, then we might see GB starting at the 4 spot, then sliding down to replace Kofi at 5 (at, say, the five-minute mark) as a transfer comes in off the bench to play 4.
However, it works, I'm seeing us at our general best next year with 2 of GB/Kofi/transfer on the floor at the same time; our specific best, when GB is one of the two and perhaps a transfer 4 is the other.