I said it in another thread, the biggest reason why Ronaldo was Solskjaer's undoing is that lack of organisation in the way we press as a team makes it less efficient, meaning players with lower stamina levels get exposed quickly. Lukaku, Martial and now to a much bigger extent Ronaldo suffer the most from this, and why Cavani had such a big impact.
A lot of Managers establish a pressing game without having to sacrifice on the ball quality for " lungs " all around the pitch. Daniel James, Lingard, Fred and Mctominay are played ahead of other more technically gifted players for that reason.
The less efficient your press is, the more you need to press. Not exactly rocket science, but it should've been clear to anyone at the club that the whole team would need to up their off the ball game significantly when Ronaldo game. He guarantees goals, but also makes it a lot more difficult to get a foothold in the game. We already struggled to dominate pre Cristiano, effectively removing a defensive presence for 50% of the time will not exactly help our ability to dominate.
This is why having McFred at the base of midfield was necessary. It s an overcorrection, adding lungs in the middle of the park to account for the loss in miles up top.
Personally, I think moving to a more possession based system will have had a similar, potentially more positive correcting effect, but the difficulty of moving to such a system after the season had already started is something to consider. You re not going to get Bruno hitting Iniesta stats, and McFred, contrary to popular belief, is not the reincarnation of prime Xavi-Busquets partnership.
And I'm having a wonderful time visualizing Wan Bissaka doing his best Dani Alves impersonation, resulting in Fellaini v Bayern type mazy dribbles that end with him tackling the ball for a throw in.
Good times