I think you keep attributing everything to the manager serghei but it is just inaccurate.
Klopp wasn't able to lead Liverpool to CL in his 1st year and lost EL final to Seville (sure some controversial decisions in the final, but also true that there was controversial decisions against Villarreal in SF too)
Klopp didn't want Salah at all, and just had to accept that the scouts decided that he is better for the type of players he wants, same scouts who identified Mane, VVD and Alison. 4 players that transformed the team the 1st minutes they touch the ball with barely any influence from Klopp.
Manu just kept getting Maguire, Sancho and such type of players instead of the Salah.
Klopp coach Manu and he will be called choker, like he was called around 30 months ago. Give Liverpool Edwards and they won't win anything.
Among teams with top players, the manager makes the biggest difference. It's pretty clear to me. Unless you can build a team with a crazy, and a disproportionate amount of talent, like MSN Barca great, and even then Lucho was no slouch, the manager is the most vital single piece.
United is an underperforming team with a lot of top players. You like to underrate players or to undermine the role of the manager in developing them. You make it sound like Salah was this huge Neymar star and Klopp just got lucky, when in fact Salah's current level is also attributed to Klopp in part. When you're just entering your prime, and you join a team perfectly set up with a great manager, you instantly go up a couple of levels, which is what Salah did at Liverpool. It's with Klopp's help that Salah progressed so well and so sudden, not irrespective of him.
Great manager + top young(ish) players + a couple of serious, fit, and committed veterans is an unbeatable combination. Add a mediocre manager instead of the top one and it all goes to shit.