Why Goalie Coaches are always old in Franchise Mode and retire fast?

I noticed that is too difficult to have a good goalie coach in franchise mode as they are always older than the other coaches and always retire fast.

When you find a good goalie coach, and sign him long term, they always retire before completing the contract. And then you have to sign a bad goalie coach again.

I find it strange that this happens only with goalie coaches, and the fact they are all old must be the cause. Can you make younger goalie coaches???