The saying “When a measure becomes a target, it ceases to be a good measure” applies very well to software development. If you’re trying to measure output / quality in software development using any simple measure you’re doing it wrong.
Measuring lines of code? Expect verbose code...
Measuring tickets closed? Expect smaller tickets…
Measuring features completed? Expect a drop in quality...
Pushing harder on these metrics when the going gets tough is only going to lead to developers gaming the metric, consciously or unconsciously.
The golden rule?
Build a team you can trust... and trust them.