On yesterday's group ride, there was one guy "Sam" who was very strong but very squirrelly on the bike. Weaving back and forth, inconsistent cadence, abrupt gear changes, braking, the whole bit. I was riding in the middle of the pack, and was doing well, as long as I wasn't behind this guy. If I was behind Sam, I couldn't safely get close enough to draft off of him, so I'd start falling off the back.

What would you do in this situation?