He's clearly a good manager. He's one of the few managers to have beaten Pep more than been beaten by him. You don't do that if you're a bad manager.
Honestly I think there are an absolutely tiny proportion of managers that are truly elite and are successful almost everywhere they go. Even the likes of Ancellotti have black marks against them. Some managers do well under tight restrictions. Some only work with huge budgets. Some are good at motivating players but cannot impose a play style on their teams. Some are brilliant in smaller teams with lower expectations and a constant churn of players.
Honestly, how many managers would you bet any serious amount of money on to do well in any job? In the last decade I would only put that money on Klopp. Pep has never had to work under any real pressure, constraints or without having the best side in the league or at least easily one of the best sides in the league. Plenty of other managers have been successful in big jobs for a few seasons before it falls apart.
Kompany has gone to Bayern and they are doing very well but do I think hes a great manager? Nope. I think that if he came back and managed a mid table PL team they would be exactly as good as before.
Simeone has found a niche at AM but I don't think he would work for many teams. Conte works well for a few years usually but eventually falls out with people. Emery failed at Arsenal but seems to thrive at teams a level down but again, I think they are massively over performing this season and will revert to something approaching their level either this season or next.
I don't think any manager is a guarantee of anything and managers have very much become a short term gamble for most teams and you replace them once they have grown stale or the tide has turned against them for whatever reason.
I will say that it does make INEOS look a bit clueless, Ole and Carrick are the lazy options and it doesn't seem like they had a plan for Amorim leaving.
I don't think you can plan for these things mid-season very well. Top managers are rarely out of a job sitting on their hands waiting for a mid-season appointment and even decent managers usually aren't wanting to come in as a limited time caretaker. They will want a proper contract for multiple years.
How many sides sack a manager mid-season and get in a "good" manager just until the summer? Must be a very very small number.