It's been touched on before - I think you have a lot of guys who more or less "top out" in their current roles...but the team doesn't want to see them leave the organization. in order to retain them they end of getting a promotion and outkicking their coverage, so to speak. More or less Peter Principle at play.
A practical example for instance. I work in healthcare, like a lot of fields our organization has a defined set of pay scales/brackets and every position falls into a particular bracket/range. That range will have a minimum pay that is the lowest you can enter on, or a maximum pay which is the most you can get raises up to. once you reach that maximum pay, you're stuck unless you change positions or have your role significantly changed/reworked and get a reclassification under a different bracket.
So something we have seen more than a few times is where you might have a bedside/direct contact nurse who gets to the top-end of their pay bracket. They are a great nurse, have been with the organization for a long time, a great asset to have around. But they feel they deserve more compensation than their "bracket" allows, and the company wants to reward them too. So they move out of a direct patient care role and into a management role for a promotion and pay raise. And then you realize they're not actually great management material. So now while you've kept that talent/asset "in the building," you've also effectively traded a great bedside nurse for a mediocre manager.
I think someone like Stenavich might be a good example with us. He was really well-regarded as an OL coach and we wanted to keep him around. He could probably get better offers and/or a new role/responsibility if he left GB... but we wanted to keep him around, so we made him OC. Now maybe that's not the best example as it seems nobody knows what our OC actually does...but you get the point. Rather than lose the person, we more or less find a role for them that allows us to reward their contributions and keep them in-house...but that doesn't mean its always the best role for the person nor does it mean they're the best person for the role. And I'm sure to some extent there is a value placed on familiarity, even if a person is getting a new role, if the club knows the person behind it well they may feel that it's a good "character" fit or someone who can grow into the role vs more of an outsider unknown.
OF course this is not exclusive to GB either, by any means. Lots of places operate similarly, same at plenty of other teams, but I do think it's helpful to keep in mind as an explainer.