There's no black and white way of quantifying a pilot's performance. Even something like number of FDM events per 100 hours cannot be an adequate measure of how well is said pilot doing his job as each and every event needs to be considered in context. When there are hundreds and thousands of pilots to consider, nobody will waste time analysing their flight history bit by bit. They will be looking for something that is more or less on the surface. Did you refuse to cooperate in a schedule revision? Did you use strategic sick leave to bridge blocks of days OFF? Were you involved in some trouble? Were there any reports concerning misconduct on your part? Did you fail a checkride some time ago? Did you try to set up some informal union or were you openly critical of the management? There you go... I've personally seen that happen in other carriers and I've heard stories of colleagues having experienced it in other carriers. You might be very good at flying planes, but if you piss off the wrong people, your going will be a matter of when, not of if.