The most common situation is that you have a new manager who's building their team. This is easily fixed (keep hiring). Next most common situation is that some

The most common situation is that you have a new manager who's building their team. This is easily fixed (keep hiring). Next most common situation is that someone wants to be a manager, and the company wants to support that purely for career or employee happiness reasons. This is where you're more likely to end up in an awkward situation.