I have long believed (and heard from others) that keeping track of commit statistics, such as how many commits each developer makes per day, is harmful to the development process. The reason seems obvious - developers will commit in smaller increments, maximising their commit-per-day number, but making it harder to bisect (perhaps all their intermediate patches won't leave the repo well formed) and harder to work with the commit history (a change will suddenly be in multiple commits, instead of just one, reverting a patch is harder etc).
Are there any studies that show commit statistics are harmful? Any elegant and well-argued article on the topic? Equally applicable would be anything about why measuring the wrong thing leads to people optimising the wrong thing, which this problem is just a special case of.