I think Ole is average in-game manager and I'll try to picture one example using game against Southampton. Before I do that, I really like to say that what Ole is doing in United is absolutely great and that he is natural football *********** and motivator that would be ideal for Football Director position at United.
Because of Southampton high pressing, we were loosing majority of our possession in trying to move ball to midfield/attack. It was easily guessed Southampton plan since our midfield/attack is too creative and dangerous to 90 min low-block defend and survive. It took 10 minutes for Ole to register that we are not moving ball forward and he moved Matic between Maguire and Lindelof in order to help defense forward play by Matic passing abilities. That move make our back 5 trying to pass ball to midfield 1 (Pogba). Southampton accepted such offer and bossed midfield next 80 minutes.
He could remedy above problem of 5 defensive positions trying to pass ball to one midfielder by moving Fernandes back, closer to Pogba so he can replace Matic in midfield and make again midfield 2 or making trio of Lindelof, Matic and Maguire more dynamic in way that one of them should move to midfield position whenever Matic drop to defense - idea being that you never leave Pogba as only one midfielder available for a pass from defense.
Unfortunately, Ole did nothing. Fernandes and our attack was cut off, ball starving for majority of the game. Southampton got midfield and Ole was passive. I know that good in-game tacticians are reacting when they see obvious problem and they won't leave team to repeat the same mistake dozen of times and expecting different result. Pep, Pochettino and Klopp wouldn't leave this situations to go for 60 minutes unattended. This is not first time that Ole is not reacting to situation on the pitch or reacting too late. That might be repeating problem whenever Ole get initial game plan wrong or situations on the pitch was changed and Ole needs to react.