We all like to use the same old excuses when we're not doing well in online multiplayer games:
"He's got to be hacking!"; "I shot her first!"; "That weapon is OP!"; "My brother must be hogging all the internet!" - you know, the usual B.S.
Sometimes, though, your repeated deaths in matches aren't only because you suck. That's because making these intricately designed multiplayer modes that are balanced enough to make sure every weapon or tactic is viable isn't easy, and more often than not the developers have to play a game of trial and error.
However that often means shipping a game - or updating one already released - and accidentally introducing a gun or item that absolutely breaks the meta (and your spirits in the process).
This process might work for the devs, but it's no fun for the player when any shooter boils down to 'use this weapon to win' and it's infuriating when you can guess what the enemy who killed you was using before you even see the killcam.