How to describe the equation of your team.

Depending on your business case, you can imagine a high fluctuation or a great retention. You never know what can happen tomorrow. I get used to this in the last years of crisis.
Maybe you remember my opinion that the teams are fluid. Having a great team at a certain moment in time, does not guarantee you that this is forever. Market is changing, people are getting older, have kids, breakup, meet a new technology, a new company is aggressively recruiting in your yard.
Suddenly, the carefully crafted edifice is down and you have no clou why the hack is not working anymore what you considered as perfect.
Your job, as manager of a bunch of software engineers, is to think what could happen and avoid the possible obstacles: change before the team notice the need to change, remove some smaller obstacles, bring in fresh air when the pace is getting slower.
The equation you wont write. But you should be able to tell it to your self and resolve it, when need it.