I dunno, it did stop all their resource income for the rest of the game and was slow as molasses too. You could conceivably engine damage it and then just make a bee-line for his base/cap the rest of the map/slowly bleed his infantry to death since it was too slow to really cover a lot of the map at once.
Most of the time the mapcontrol no longer mattered. You could only stop the ace if you were already winning hard. If it was an even game, with both players having the same army count, the free tiger ace would give the german player so much power that they could just move up and base rape you with their entire army.
Most players were bad and only called it in when they were losing badly, or they forgot to call in an extra pio with instant vet 3 and give them a sweeper before calling in the ace. Bad usage of the unit by most players just make this unit appear to be somewhat OK balance wise. It was not.