I'm wondering if, when you join a free play match late and either revive zero xp or extremely low xp, is there a system to not include this in you average stats per game? Early on I didn't care but as it started to happen more often it's begun to get on my nerves.

No, the statistics are just very unreliable and broken really, allot of the time they dont even record your stats or miss allot of things out. Every time a migrating host happens [which can be allot] your stats are deleted.
And everytime you enter a mach late or enter and exit a match [which can be allot] it counts as your average Xp per game. The stats are just borken lol

Not to mention that they only record online matches- for ALL your characters...

So much for "blurring the lines between genres", eh?