The sample size is a bit too small. The trace does not show any problems at all.
When you disco, you need to run the trace/Ping Plot immediately after the event, and set it to run for a minute, or two. That should yield valid results.
If the trace/Ping Plot looks fine, then try renaming the games "settings" folder and see if the problem persists.
If it does, then start looking at software which might interfere. Anti-xxxx, security software, iTunes and so on...
If you are a wireless connection, see if you can hardwire the connection.