Sinestra parses started showing up on World of Logs. A new boss being killed will change up stats for a while.

No, that doesn't seem right. It was a massive drop for two days, March 5 and March 6, after which it popped back up again. The dip is also more apparent in the "all parses" versus "top 100"--I highly doubt there are enough people working on Sinestra for it to make that big of an impact.

Seriously, go look.

It's definitely Sinestra. The way Spec Score works is that a boss doesn't factor into the calculation until it's been killed - if all specs have 0 parses for that fight it's completely left out of the calculation for the Spec Score. If a boss has been killed and there are no parses for a spec, they get a 0 on that fight. Having that 0 appear all of a sudden drops their Spec Score way down until they actually have some data on the fight.

Look at the Sinestra-specific data:

http://raidbots.com/dpsbot/Sinestra/25H/all/14/60/default/

For example, first date ele shamans show up in 3/8 while the first data for other specs is 3/6. Only the specs that didn't show up in the first few days show the drop. The same is true of the other specs with the dramatic. Once they show up on the fight, their 0 turns into whatever percent of the top spec is and that raises their average far higher.