Now I don't pretend to be the worlds foremost expert on rushing. However, I do rush from time to time. So these are my thoughts on why rushers do what they do. Before I get started I'll tip my hat to my friend G whose "Inside the mind of a Camper" threads inspired this post. Now back to topic. First, this is not inside the mind of a headless chicken. That would be too short of a discussion. This is for the guys that rush and do very well at it.
The rusher in general likes a lot of action but more importantly he bases his game plan on catching his opponent off guard. Unlike camping which depends on controlling a particular area(s) of the map, the rusher is primarily focused on getting behind enemy lines as quickly as possible so that he can defeat the enemy strongholds and disrupt map control for the enemy. Rushers will flank relentlessly and if they get behind enemy lines they can wipe out entire teams in the blink of an eye. I can't tell you the number of times that I've come up on a enemy team that has posted up and is actively engaging my team rather successfully in head to head combat. But when I come up behind them and drop the one guy that is watching their backside, the whole team is soon to fall. Once this happens spawns tend to flip and the ensuing chaos can cripple the enemy team via random spawns provided your own team can pick up the flip.
Like I said, the rusher wants to be inside of enemy territory. He will use speed perks, weapons and routes designed to get into places faster than you think that he can. This gives him a huge advantage in the gun fight because quite frankly you aren't expecting him to be there yet. He will often run a silencer on his weapon but often he doesn't run off the grid. The reason being is that the silencer allows him to take down groups of enemies quickly without being noticed and he fully intends to use his ping on the radar do distract his foes. You have to remember that the Sat Com ping isn't in real time. It is often just reporting your position about a second ago. The rusher is on the move at all times. So he knows that someone will be approaching where he was. He uses this to his advantage. He will take his kill and then proceed to make a quick getaway along a flank route designed to limit his exposure to enemies but also to provide him access to get behind those that are chasing his red dot. Real time map awareness is critical to successful rushing. At some point he is going to turn on his enemies and make them pay for chasing his red dot.
Now to take a look at how rushers affect different game modes. TDM is a pretty obvious one. His tactics if successful will put him in position for a high number of multi-kills to a low number of deaths. In KC this along with his desire for close combat engagements and speed perks puts him in a great position to pick up tags. In DOM, this guy may or may not be a flag capper but he naturally will provide a distraction to the enemy which often will allow for flags to be capped. An enemy that gets shot in the back too much on the way to a flag will at some point forget about the flag and find that rusher before moving on.
So there's my first read through on Rusher phycology 101. I've probably left out some important details along the way. But that's where you guys can help me to better define why successful rushers do what they do. Personally, I enjoy rushing but my playstyle overall is a blend of rushing and camping techniques. I find that to be most effective for me and that's what is most important. Knowing what works for you and applying it. However, I do think that it helps to have an understanding of what the other guy is thinking. If for no other reason but to better prepare your own game plan on how to defeat him.