I agree with Khaled here.
There needs to be some broad obligatory targets in terms of results. For example, he can't drop lower than 3rd in La Liga. Reconstruction or not, you can't have more than Madrid and Atletico finish ahead of you.
And you have to get out of the group stages in CL. Here, depending on the draw, you could expect quarters or not. Semis is nearly impossible without getting very lucky.
Those would be his obligatory targets.
But the main criteria is how the team plays and how we will fix the current big flaws of the team, which are:
- too many old players in the first 11
- lowest work-rate in any top side in Europe
- least amount of cohesion in our tactics
In other words, he needs to play young players, we need to work harder on the field, and we need to have a clear way of playing where everybody contributes according to his role.