Both Guardiola and Zidane had no experience what so ever. I would argue Solskjaer had more experience than both when taking over at a big club. The difference is the squads they inherited were vastly superior! People also seem to have short memories. Solskjaer schooled both Chelsea and Arsenal in the cup and Spurs in the league when he first took over! What is happening now is do with something different than tactics.
Whats happening now is a combination of a very thin squad coupled with important injuries and the players that remain not being on form. When we went on a run that was essentially title winning form last season we had almost a full squad, we still had Herrera and Lukaku (Lukaku wasn't vital but was important) and we had the new manager boost. Going from a very toxic dressing room to one with Ole must have been great and gave them a massive boost. That all came crashing down literally the second we appointed him on a permanent basis.
This season Ole has shown that he doesn't have the ability to actually create a style of play or coach attacking transitions into the team. What he did in the summer was great. We desperately needed another midfielder but the players he got rid of and the ones he brought in were great. The problem is that we have come into the season in a fragile state and been punished for it. With such a limited squad we cannot afford to have a mis-firing Rashford along with injuries to AWB, Pogba and Martial.
I don't think Ole is the right man to take United forward but currently the squad and injuries we have is doing him 0 favours. Come next summer we won't have Pogba so it will be interesting to see A) who is our manager and B) who we bring in because we need another 4 players to compete. 4 top class players. £250m worth at least.