I grew up in an old suburb with four-way stop signs on every corner. Everywhere you drive, you're expected to come to a complete stop every few hundred feet. It's irritating, and it means people only obey the stop signs if there is another car at the intersection, or a cop visible.
My wife and I spent part of our honeymoon in Berlin, where most of the small intersections--the kind that would be four-way stops where I grew up--are small, single-lane roundabouts with no stop signs or traffic lights at all. This seemed crazy to me, like traffic anarchy, until I chatted up a local and learned how the roundabouts work. When you approach, you yield to the right. If there's no one to your right, no need to stop.
As you're making changes to the way your team operates, are you putting in stop signs or roundabouts? If you put processes in place that are onerous for your team to follow, they simply won't follow them. They'll blow the figurative stop sign whenever you're not looking. This makes it very hard to improve on the process over time, because no one is following it in the first place.
If you want to improve your team's performance, start by observing how they're already working. Find a place in the process around which you can introduce some structure to what's already happening instead of adding a burden that stops forward motion. Observe the results of that change for a little while, then make your next change based on what you observe. Repeat ad infinitum.