10Gb Update for black ops?!?

I haven't played black ops for a while... maybe a little over a month so i booted up steam for a quick game. I wasn't surprised when black ops started updating... i was expecting it to. It started taking a while so i looked to see what it was doing and it's trying to download a 4.7GB update. And that's just multiplayer... there was another 4.8GB single player update. Does anyone know why they're so big. Maybe the new maps or something but i haven't bought them or anything. My friend hasn't played for a while either over a month and he booted up steam and black ops updated normally just with a 700mb or whatever file so is someone able to tell me why i'm hit with a 10GB update?!?! Thanks

Me and my friend play on PC btw