Well 4 of them are supports so they aren't suppose to get CS and the other two are junglers which don't usually have the same CS as laners, even though that's pretty terrible, I can't see their rank. You also forget the fact that some people are one tricks, like I was last season where ALL I could play was Veigar, and whenever I was put top I could ONLY play Kennen which wasn't as good as my Veigar.
After looking this over a little bit, however, the original person was probably a "support main" and you know the rest. The problem with Riot banning them is the don't have any solid proof of people boosting besides the IP address constantly changing, but they're never gonna look that over, but it could still be fool proof by having the original person not play AT ALL while the other person across the country/world plays where this "could" be simulated as the person moving to the other side of the country.