Let me back up a bit and explain what the operational evaluation does for you.
At each change to an aircraft design and, in this case, stepping from what we call the NG version, or the previous generation to the Max, the manufacturer will propose a training program that bridges, from the pilot's perspective, the knowledge and awareness they have to operate the aircraft from one model to the next.
The OE, in its simplest form, is a joint board that evaluates the appropriateness of that training material to get a pilot who has flown the NG to fly on the Max. It's as simple as that. If the OE board determines that the training proposed is sufficient, then the conclusion is that it is operationally suitable.
If there are issues when the evaluators go through the process.... There are always naive candidates who are selected. We try not to get people in there who have predisposed knowledge or are biased in any way. We're putting regular, average line pilots in there. They do the evaluation. If there are issues, if they struggle and are failing on the simulator, that is a clear indication that the training proposed by the manufacturer is not sufficient, and there will be an iterative process to improve the training.