In a recent interview with Destructoid, David Vonderhaar talks about how Treyarch has created a new system called "Black Box" that analyzes player data to really see how everything is performing, just like a plane after takeoff.
""What we said was we need to balance the emotion of using something, like your personal visceral reaction to it, with math. There's a lot of instrumentation in this game, there's a lot of data logging, so I know exactly what the power band of a weapon is at all times. So I can combine how something feels with how it's actually behaving. I know, I know this is going to happen: A million people are going to Tweet me and tell me that the [for example] 'PDW-57 is overpowered, Vonderhaar what are you doing?'"
"What I'll do is I can go and look at the math and I'll go 'Actually, you know what dude? You're just good with it. Have fun, because the math says that it's not overpowered.' I have the averages, you're being successful. That means Pick 10 is working, and if it's overpowered I'll know it for real. Like not because someone said it was, or because I felt it was, or because you sent me an angry Tweet because you got killed by the SRM Shotgun one night 17 times so you're mad. The data will tell me the truth."
The Destructoid article is a long read, so you can find the rest of it here.