An interesting post stolen from reddit, by someone who actually knows Berge well:
u/tryling2310h
I wouldn't be surprised if Berge flops.
Discussion
I've watched pretty much every minute of football Sander Berge has played since he made his debut in Norway and I have my doubts he'll come good if United plans on using him the way they have in his first few appearances.
When he first arrived at VIF and played for their 2nd team at 16, the reports weren't universally positive. A technically sound player who could pick a pass and had just learned to use his frame well. On the other hand he was "slow" and "lazy" and people doubted if he'd ever be up to the speed of the Norwegian top flight. The Norwegian U21 manager even used that as a reasoning for not picking him a year later when he had started dominating in the top flight(A few months later he made his debut for the senior team).
Nevertheless he was among the best players on his team. Their best if they had a bad game, top 3 if they had a good game. His role in this team was to get the ball (from friend or foe) and move it to Zahid (Free-roaming playmaker) ASAP. He could also run forward with the ball at his feet if the pass wasn't on. Passes to wing backs bombing down either side also became part of his staple.
He got his move to Genk. Funnily enough the reports there were the exact same. After 2 training sessions people doubted he'd ever play in Belgium, after 2 weeks he made his debut and would've played every minute of every game since if not for injuries. His role in Genk was very similar to his previous role. Get the ball to Pozuelo or Malinovskyi, watch the magic happen. He looked like Moussa Dembele with the style of Busquets. I think it's a shame the Genk team that started their title-winning campaign never got to play CL together, it's the most entertaining team I've ever seen.
As the squad that laid the foundation for Genk's championship fell apart, his role changed slightly. Hagi and Nygren (Replacements for Pozuelo and Malinovskyi) flopped and so he found himself with more offensive responsibilities. While nominally in the same position, he would carry the ball deeper into the opposition's territory and make under lapping down the right and cross. His starting position was never ahead of the ball.
In the interest of saving both of us time I'll skip ahead to when we was re-linked with SU.
It seemed like a good fit to me. The teams results speak for themselves and they had a role in the team he seemed perfect for, currently occupied by Norwood. It also seemed like he had been scouted well over a long time, which is always a positive. When it comes to the possible shortcomings of the player himself I wasn't very worried beyond the fact that absolutely nothing is a sure thing. He didn't look out of place against Liverpool, Napoli or Spain, showing some glimpses of his best.
So the day rolls around, maybe he'll get 10 minutes if he's lucky and the team are a few ahead? Surprise, he's starting! ...As a box-to-box player? Is Lundstram injured and they just need bodies, perhaps? Nah, there he is on the bench, seemingly fit. Since then he's kept the same role and I'm really disappointed. By playing in the role he has so far, you've effectively removed the things from his game that make him truly special. Not that you can't make use of being a good footballer in any role, obviously.
As someone who knows the team better than I do, is there a chance he'll ever play the deep role? Maybe as a part of 2 when playing more dominant teams? Sorry about the rambling, I just care way too much about something I have no real power over

Here's to Sheffield United clinching the Champions League spot and Sander Berge turning into prime Pirlo!
TL;DR: Sander Berge is being misused in my opinion and I suspect he won't be a success. Even if he becomes a world-beater box-to-box midfielder I'll miss what has been my favourite player stylistically the last few years.