I agree with what drift0r said in one of his problem videos, for whatever reason after about an hour or so the servers crap out and the game gets horrible.
Yeah, I have no idea what the hell is happening in those types of games, it's mind bending what is going on, what's even more strange is you can tell when "it" swings back and things work again and you start to melt people.
Problem is going for camos/dark matter people head glitch for headshots, then the secondary problem is people want a high KD/beast gameplays to upload to their 5 subscriber YouTube channels.
I forgot to mention above but ties in to the first part of your post. The fact "it" seems to change mid game as well. It is rare but occasionally the two halves of domination can feel like different games. I can do really well in the first half, have a good number of captures a 3 or 4 k/d and be top of the team but by the end of match be negative and at the bottom.
Camo's is a good call but I doubt youtube, some of the kids you come across doing it have 0.X k/d's low SPM and constantly camp the same spots so doubt they have ever had a beast gameplay to upload to youtube

Sometimes at the start of games i get the countdown and it varies between 5 seconds and 15, I am assuming the 5 second countdowns are when you're on a dedicated server??
That has happened on CoD's for ages, I think it based on how quickly you connect to host.