There is a defensive play Nickel 3-3-5 Cover 2 Man Under (http://plays.myfootballnow.com/252-medium.png) that my offense has a negative familiarity of -15% against. I assumed the familiarity is between 0 and 100%.

In the last couple of games I noticed a lot of dropped passes against this defense.

Is this a bug or what can I do to improve it other than scouting?

nods it's a bug. :(

Just clear it from your mind and don't focus on it.

Its above maximum familiarity for that play.