traffic was measured from both the F5 pool member statistics as well as the server side session table.. The server will always reflect the most accurate number of sockets that are in EST or TIME_WAIT state for example.
None of the things mentioned in that article apply here. Since I have seen this with Round robin that eliminates it being just with least connnections. This is one of those issues that I would need to get at the internals which I cant do without support. For example with some other vendor devices I can turn on specific types of debugging and observer the decision logic on where a request is sent based on the current configuration which is very helpful in these cases. It would at least provide some logic as to why more traffic is getting sent to same set of servers.