(Siege's only problem, by comparison, is when your teammates don't work together...)
Like you teamates argueing over Timmy(The rookie), which ends up getting Timmy killed. Teamwork is hard to understand for some people.
YES, THIS. OH MY GOD. i have this happen to me a lot of the times, and i REALLY DON'T MIND it if only the other player wouldn't lead the rookie to a horde of enemies! there was this one game on steel beast where my partner took command of the rookie (mind you i had the rookie throughout the entire match) and led him STRAIGHT to the gnezdo mini boss. i was heavily pissed when i saw his health go straight to 1%.
If you think getting singled out for being top scorer during a match is bad, think about what happens when you're ranked top 10 in Predator. It's impossible to host matches sometimes because people see your name and try to snipe your room or they figure, "This is a serious play room," when all you want to do is play with friends. They come in and try to wreck shop, everyone gets mad and starts playing very serious, and it's a terrible time.
YES, THIS TOO. i have a friend who is a top-ranked player in predator on re.net with a lot of wins, and he tells me all the time that players he doesn't even know joins his game and go against him with ada/ sherry's pipe bombs and the in-game grenade and rocket launchers. sometimes as the ustanak, players grab him and then flee the battle, going into the corner, or continue to run around with him in his claw.
it happens to me in siege as well. i've gotten a few messages from other players about my siege rank on re.net. i've had "spies" on my team before too (players working with someone on the other team). sometimes i get kicked as soon as i join a game as the host's opposing team.
my wins don't mean anything, especially on siege since it is not score based like the other modes.