My experience is that 99/100 matches there is at least one red bar player.
Also from my experience i can say that one of those red bars is the host.
And the host has red bar, because everybody is playing on his connection.
Probably he has a very good ping, but too poor bandwidth for all players to play on. That's why red bars are mostly MVP's- they are hosting, so nr. 1 connection which counts.
This is the reason that after 2 years there are still red bars, every match......Bungie won't ban them, because they know it's P2P's matchmaking-system's fault.
Everybody knows that when you have very bad internet (red bar), you can't make a kill. Have tried it myself.
-
Red bars are a)the guys with crap Internet, b)the guys 3,000 miles away from you and/or c)scrubs running lag switches.