I believe PVR rate is a complete red herring. If you want to see the real exit rates from the Armed Forces have a look at how many are leaving at a break point/optional retirement date i.e those who are turning down an offer of extension to service (inc the promotion that goes with it). Don't think they track those stats and if they did they certainly wouldn't quote them (the grapevine suggests 95+% of pilots are leaving at their 38/16 point ....)
And of course the quoted figures, particularly those that state all is well because we are 90-odd% manned, fail to reflect experience levels. Do people really believe a fully qualified pilot/technician leaving after 20 odd years and umpteen operational tours can be replaced in anything other than numerical terms by a FNG/sprog? Manning balance perhaps, but certainly not experience balance.