Negative run Differential winning championship

I just got bounced out of the playoffs and noticed the two teams playing for the championship both have a negative run differential. Seems odd. Have you ever seen this? Is it somewhat common?
http://forum-365.strat-o-matic.com/archivesn/
http://forum-365.strat-o-matic.com/archivesn/viewtopic.php?f=12&t=275184