There is a difference between passing the training being a good atco.
Keep in mind that(for example) muac has a very high workload.
And these numbers such as 50% are official numbers,published by eurocontrol itself.
I know that it's not what you want to hear. But i think it's better to be prepared, that many fail the training insted of thinking"i passed the feast so i will not have any problems with the training".
;-)