Flock Effect
From KruelWiki
Sheep are more powerful when they are sticking together.
My guess at the approximate help they get when they are together is def / (x+1) where x is the distance, and def is the defence of their ally for defence. A sheep would only obtain a quarter of that for attack as there's not much they can do to help in the firing of dropping apart from some helpful advice.
So, if our sheep Adam is popular with the lady sheep Betty, Clare and Debbie, and assuming they all have a defense rating of 5 then his effective defense rating would be 5 + 5/2 + 5/2 + 5/2 = 12.5.
Now the downside to this is if our sheep are under attack and they are close together, then an unaimed shot will likely hit one of them. So just attacking a flock will likely damage a fair portion of them.

