I just started tooling around with leagues.
Based on the two I joined, the default behavior of "League gain" was that it started at 0%. But I noticed someone joined a league yesterday with a non-zero gain (obvious because the person was immediately vaulted to first place). At the time of this posting, the league reports the prior day gain for "joeoftexas" was 0.01%, but his league gain as 4.53%, despite having joined yesterday. Maybe this is because he was a member previously or something? Anyway, just pointing it out. . .mostly because I thought I was going to make a run for the lead!