One of the things that I like to anecdotally measure is how long a similarly complex change takes. Over time, if it takes longer, then you're likely suffering from tech debt issues. If you're able to turn things around so that it starts getting done faster, then it sounds like you're starting to turn things around.
On the missed deadlines issue, that reminds me of a blog we posted a while ago about why we stopped estimating ongoing development on these types of code bases[1].
I also like to use the metaphor of a car that's stuck in the mud (or snow). The wheels Are spinning really fast and the engine is working really hard, but the car isn't going anywhere. It's only when you start trying to dig it out that you start to see forward progress, and even then, the progress is slow at first.
On the missed deadlines issue, that reminds me of a blog we posted a while ago about why we stopped estimating ongoing development on these types of code bases[1].
I also like to use the metaphor of a car that's stuck in the mud (or snow). The wheels Are spinning really fast and the engine is working really hard, but the car isn't going anywhere. It's only when you start trying to dig it out that you start to see forward progress, and even then, the progress is slow at first.
[1]: http://corgibytes.com/blog/no-estimates/productivity/custome...