Everyone is undermanned. I've been flying for 10 years and when I was new guy I used to fly 2-3 times a week. Now if I get that a month I'm lucky due to the cuts to the FHP. We, as an Ops USAF, do more training now in the sim than ever before. A byproduct of that are sorties are even more valuable for training, checkrides, etc.
Want to retain maintainers? Get rid of chasing metrics, as a leader learn how to hear (and say) no when asked to do something improbable, and bring back certain reenlisment bonuses, and stop making the MX community cutthroat.