I imagine that the rest of the rabbits will stand against weasel, so he will have only enough time to injure one rabbit. After that he will follow the group, expecting them to leave injured behind, so he/she won't slow them down. However, if they decide to march as fast as the wounded, then weasel will have easier job to keep up with them.
Pessimist sees a dark tunnel. Optimist sees a light in the tunnel. Realist sees the light of coming train. And a driver sees three idiots standing on the track.
"My heart has joined the thousand, for my friend stopped running today." - Watership Down by Richard Adams.