While not as applicable in situations where the engineering team isn't under much pressure to deliver, there's a pretty common negative feedback loop that can occur with engineer staffing. While under pressure, teams with an adequate or bountiful number of skilled members will generally perform pretty darned well and not have a problem. If anything causes the balance to start tipping too much in the ratio with unskilled team members then the skilled members will feel more internal career growth based pressure to find work elsewhere. As they start to slowly phase out to other locations the ratio gets even worse, the quality of the product gets worse, and the moral gets worse. All of this causes more incentive for the skilled engineers that are still left to leave as well.

Unfortunately as this happens a higher number of deliverables will be missed and more bugs will arise alerting management that they somehow have become a less productive shop. This is where you can readily identify bad engineering management. Instead of tackling the root of the problem many places double down by increasing pressure to deliver and by relaxing standards as to who they hire. Once this happens you've unfortunately started the process of being a sinking ship. This can be righted in time depending on how large the company's coffers or how tight of a hold they have on the market but growth generally will have peaked by this point.

What management should have done (or needs to do ASAP) was to start trimming poor performing engineers. Yes firing people is hard, yes it sucks getting rid of workers when you're already behind schedule. But any good engineers you manage to trick into joining this dysfunctional team will likely leave within the first few months anyways. Relaxing pressure to deliver WHILE fixing the poor performers issue can also help slow down the rate you're losing good performers at least for a short period.

I've seen this at many many places. Currently still in one of these situations because they keep throwing more money at me to stay but even with that I've started looking again because the situation is not helping my career growth as much as I wish.

edit: IpV8's checklist is also really important to look for and lack of that could cause the start of tipping the balance as mentioned above.