Round-Robin has always been flakey in my opinion. It will count any connection attempt as that servers turn in the rotation being taken and rotate to the next server.
I would suggest going to Least Connections (member) or Least Connections (node) and see if your connections Level out if Server Load is your major concern.
Least Connections (member) - Load Balances per member of the pool. I doesn't care about the actual load on the server, or the number of overall connections to the server, just the number of connections balanced out in the specific pool you apply this to.
Least Connections (node) - Keeps track of the total number of connections on the entire Load Balancer and compares that number to the total number of connections for the other servers in the specified pool. Server with the least number of connections gets the next connection. (with this setting it can APPEAR to be unlevel, but if you look at the comparison of the Nodes, you will see that it is even).