A couple weeks ago, we had a little debate about whether or not Github's punchard graph was at all meaningful. I felt strongly that the punchard graph does a good job of highlighting project differences; and, if nothing else, gives a rough indication of what might be going wrong or right.
There are some caveats. You need to have some insight on the project, such as team size and complexity. You also need to make sure the system isn't being gamed (not all commits are created equally). Still, all things being equal, consider these two projects and tell me which you'd probably rather work on, and which you think is more likely to succeed. Or, if you refuse to make any assumption, what questions would you like to know from each team? I know I'd want to know completely different things from them.