It's possible due to a variety of reasons (e.g. config set up incorrectly) that CLs that could have been reverted aren't.

Consider implementing an alert that incidates an unusually high rate of these.

Some ideas:
* no reverts within a certain period of time
* culprits matching the criteria to be reverted found, yet too many not reverted (e.g. 5 culprits identified within 24 hours with 100% confidence, yet 0 reverts created)