I don't know whether this is already in place or not, but flag captures shouldn't count if there is nobody on the other team. I joined a public CTF with two people in it, soon after I joined one guy left (probably got booted) then the host switched teams to boot me, and I'm fairly sure he was trying to boost his flag captures without any competition.

Also, I think Kill/Death stats should be removed from CTF and any future objective gametypes. It would encourage more people to play as a team and actually capture and defend, instead of just farming people to pad their stats.