Just because there was an offer of 20 keys in Sale #2 doesn't make the 15 key sale an outlier, it's still well fit in the range that it wouldn't be considered an outlier.

Also in sale 1, it looks like it didn't sell for 15 keys, it sold for a DBD Little Buddy

http://backpack.tf/profiles/76561198057814273?time=1443769200 - 9/28 - 10/02

No outpost link

But in this guy's bp history, it does look like it sold for 15 keys

http://backpack.tf/profiles/76561198055212937?time=1443250800 - 9/26 - 9/28

No outpost link

The thing is, neither of their names are found in the histories of the keys nor the unusual, but infiniti is in both the keys and the unusual's trades. It was either infiniti was brokering for one of them and got the guy 15 keys for the prancer, or the Flat Mango quickly bought the DBD little buddy right after the trade happened, which can happen and bp.tf history doesn't pick it up.

I would wait for a mod or bp.tf premium suggestor to clarify that trade, but as far as I know, 15 isn't an outlier.

Staying neutral on this one.