The main problem is not sticking with the blueprint.
After lockdown when Matic Pogba Bruno was flying, we all knew we finally had, at the very least, a blueprint of a top midfield. However when that setup started getting cut through, instead of adding an additional body but still keeping the technical base, Ole binned it off entirely in favour of pure workrate.
The thing is, it's actually better for the team to keep the technical blueprint even with an older Matic, because that way the transition to a younger technical DM would be smooth. That's how top managers like Pep and Klopp do their squad building, they don't directly contrast their core philosophies regardless of the results. Something which Ole was guilty of, and it seems like Ralf is doing currently.
Regarding the midfield, even if players like Donny and Matic don't offer as much workrate and protection as Fred and Scott, a top manager would still stick with them because he understands the importance of imprinting a possession-based blueprint on the squad. And of course if the board is able to see what he is doing and back him with funds, he can then get more quality replacements which still fit the same technical blueprint, and thus transition the team to a new level.