[alexnking]

"Our dev team is no longer producing quality work at a pace fast enough for the business. They're complacent."

B does not follow from A. Just because your team is not producing "fast enough for the business" does not mean they are complacent. It may simply mean the business has unreasonable expectations. Outsiders (especially non-developer outsiders) cannot really give you any insight on this, as all codebases are different, and the time it takes to fix a bug or add a feature will vary depending on the amount of technical debt and complexity that have accumulated.

Your team however, is in tune with your codebase, and appear to be able to tell how long things will take (you don't mention that their estimates are inaccurate, just that you dislike the estimates). If you would like the amount of time it takes to be different, perhaps instead of assuming they are complacent, it would help to ask what needs to be done to make changes to the codebase faster. The answers you get (such as a higher level of test coverage to increase change confidence) might surprise you.