EHM The Blue Line

Is there any way to develop staff stats? I'd love to use some retired players as staff but they are always terrible and have lots of 1s

I believe the retired players turned staff are randomly assigned tributes. You can't develop staff. For example sometimes you will see a retired forward have good goalie training attributes.

The staff attributes develop spontaneously until the person reaches their potential.

Coaches who have a small difference between their CA and PA tend to only grow once in their early 50s in my findings. Coaches with a large difference between their CA and PA who are young (in their 20s or 30s) will tend to have their attributes grow twice, once in their early 40s and once in their early 50s. Jay Leach is a good example of a very young coach whose PA can be high enough that he has both growths. The only really good retired player coach I've seen in very close to 3000 hours of gameplay was a Japanese player turned Coach named Denis Akimoto. If you want to keep a player around as staff for sentimental reasons I'd generally suggest trying to sign him as a scout and using him as your "next opponent" scout. That way it really doesn't matter much what his attributes are.