Modeling tank crew casualties is a bit of a grey area, not many people actually die in their tanks when it is penetrated surprisingly enough.
The South Alberta Tank Regiment (part of 4th Canadian Armoured Division) lost around 180 Shermans from August 1944 to VE day (300% turnover rate!), and suffered 100 deaths. Of those 100, only 10 died inside their tank by a shell/burned, the rest were killed in accidents, shot down while bailing out (biggest single cause), caught outside their tanks by an arty barrage, sniped while peaking out of their tank etc. This is probably not too surprising, once a shell goes through your tank or it is immobile, you usually bail out before a second shell enters and finishes the job.
On the other hand it was found most crews were wounded in some form when they bailed out due to over pressurization within the tank when it is penetrated. A penetration often knocked the crews silly and one of the most common wounds from a penetration were burst ear drums.
The penetration mechanics are probably not too far off, its just players (especially in this game since you are locked in your tank) will go down fighting.