If you have more than 100 follows or unfollows since the previous check, Joule displays "Many" instead of the names. (This used to be "Hiccup".) The three reasons for this are:
We have to do a separate lookup in Twitter for every userid we haven't seen before, to get the icon and username. For 5000 changes in a day, that slows page load times a lot. This is still a problem.
There is an old pre-Twitter assumption that 100 follows or unfollows means either that Joule broke, or that LJ broke when it sent us the names. Clearly this is outdated.
There isn't enough space in the chart for more than a few hundred names a day without making the page insanely long.
Carmen has suggested replacing "Hiccup" with a link to a sub-page which displays all the names for that day, possibly allowing paging through them to get around the first problem I mentioned. I think this is a very useful idea.