Then it's not modeled correctly, well sort off. If dynamic pressure is blocked (pitot) your ASI would show no change in speed regardless of power changes. If you decent, it will overread and if you climb it will underread. Unless there is a leak in the system it will never drop to zero! MSFS also models this incorrectly. If there is battle damage to the pitot I would imagine that there is either still dynamic pressure present which will lead to fluctuating incorrect ASI readings or the thing is blocked which will lead to the readings above. Of course you could argue that the pitot pipe is cut off and bend away from the airflow now which makes it another static port in which case the ASI would read zero ;)
If static is blocked then it will read roughly correctly for straight and level and just the reversed as in pitot blocked in climbs and decents.
