In what ways were the bad managers bad?

I wrote the grandparent comment on how to be a good manager. Hardly an expert but perhaps I can offer some insights.

Managers will have a mix of skillsets, but it's very important that they're at least passable on EVERY metric.

"Bad managers" tend to be those that flunk the hell out of one metric. If you're terrible at any one specific thing it'll bite you. e.g. You're technically strong but you can't manage egos and keep telling your underlings they are useless. Or conversely great leader but can't tell your debits from credits.

Manager job is to keep all aspects under control. So half the aspects managed very well and half crash and burn is not an acceptable outcome.

Among underlings bad manager = unreasonable expectations & no coaching mostly.