Not ready for development backlog is taken into work
A combination of the following issues:
Not ready for development stories are taken into Sprint backlog
There is no Definition of Ready criteria
INVEST principles are absent or/and not applied in DoR
Discovered by combination of metrics:
Velocity: Committed vs. Completed, when team cannot meet commitments due to new or/and change requirements emerging during iteration execution what, in fact, exceeds capacity
Scrum Cycle Time, when ideal time of feature delivery cannot be predicted as scope is fluctuating, thus cycle exceeds due continuous requirements refinement process during active iteration
Lead and Cycle Time, when ideal and elapsed time of feature delivery cannot be predicted as scope is fluctuating, thus cycle exceeds due continuous requirements refinement process during active iteration
Sprint Plan Change, when priority stories are replaced with less priority stories (because they are better refined)
Backlog Health, when low indicating that there is no enough "ready for development" scope to fill out several future iterations
Requirements Rewritten After Became Ready, when there are frequent updates in the "ready for development" scope in sprint backlog during active iteration