I couldnt answer that question for the US Army/marine corps however I can say that there is a vast difference between loosing a 10 year pilot to a 3rd or 4th year pilot in the Army.
Speaking loosly, in the civillian sector once you get you ATP ticket there really is no concrete measure of experience that actually affects your capacity to do your job. By this I mean a 1500h ATP pilot can 'do' thier job as much as a 10000h ATP pilot can....i.e: get plane from a to b.
In the army however the difference is exponential between a 4yr and 10 year pilot. But the military uses civillian metrics (pilot in vs pilot out) to measure its shortage. A mil guy not only needs to fly but then needs to go through multiple mission upgrades. Probably 20 to 30 up to a ten year point generally culminating as a flight examiner.
My point, and I have argued this before, Army needs to measure the pilot workforce in both numbers and man years to get a true reflection of the workforce.
So.....if Army thinks they are short in the raw numbers then if they started to look at skills lost
using a man years metric I would posit the defecit would be staggering.