In a typical TF2 game, you will have 12 players on each side. That is the main draw of TF2 for me, since the larger team size means a team can dedicate one or two players to carry out what will be rather unorthodox strategies for a 6 man team.
For example, on a 12 man team, having one person dedicated to be a distraction can really pay off if said person can reliably draw away more than two people from the fight. Even when he can’t do so 100% of the time, which is definitely the case, 11 VS 12 isn’t as bad a disadvantage as 5 VS 6. The rest of the team can at least hold on until the distraction strikes and give a full push while half the enemy team is looking somewhere else.
And in a normal pub game, if you’re annoying enough, you can get at least one third of the team to actively hunt you down for at least a minute. One of my favourite moments in TF2 is when on a half-filled 2Fort game, I managed to get half the enemy team chasing me as Pyros after I backstabbed them a few too many times. That said, while I was cackling madly when I saw them chasing me into my spawn flamethrowers blazing, it was rather horrifying for me as I was a rather mediocre Spy (and still am).
A distraction, however, isn’t just meant to shift the player numbers into your team’s advantage during the main fight. While turning a chokepoint fight into a 11 VS 6 situation with a well-done distraction is certainly great for the team, the main objective of being a distraction is to draw attention away from the objective and onto you, so that your team will have less hassle contesting the objectives because some otherwise very tough-to-kill enemy team members are busy chasing you across half the map.
Just to be clear, while a distraction is a flanker, a flanker to me is not necessary a distraction. To me, a distraction is specifically meant to harass , and not to make picks. Sure, if you get the chance, go ahead, but that isn’t your top priority as a distraction.
A distraction is meant to be a constant pain in the enemy team’s side and keep them in a constant state of paranoia. You need to make them constantly look behind them for you instead of looking in front where the rest of your team is. I cannot emphasize the word “constant” enough. Your top priority is to survive. Unless it is absolutely necessary, you should never risk your life for a possibly suicidal kill. A distraction that is dead isn’t exactly distracting unless your ragdoll looks hilarious. Only when you can get your team an absolute advantage and you being a distraction no longer works out, then you can risk your life for that kill.
A distraction should have at least semi-decent DM skill. Mainly because you need to be able to punish whoever doesn’t take you seriously so that they have a good reason to look out for you. Besides, if you aren’t much of a threat, even if you manage to severely annoy the enemy team through some other method, they’ll be able to quickly kill you and get on with their lives. And you better hope your 10 seconds of of fame allows a teammate a lucky break to kill them, or that’ll just be a waste.
But above all, you need superb gamesense and map knowledge. You need to know the flank routes for your escape, the health and ammo packs, and above all, where enemy players will be hanging out. You also need to know when to hide, when to strike, and when necessary, when to fire a flare at the enemy team and run away cackling while everyone else is either looking for a Medkit or you. You need to be constantly on their minds, setting them on fire, shooting them from just outside their view, knock them off their perches, and most importantly, annoy the living hell out of them until they’re reluctant to even round a corner just in case you decide to pop out and tick them off again. Killing is not essential, as long as they’re no longer at a position advantageous to them and bad for your team you are doing your job.
Also, you need to be able to annoy and harass as many people as possible. With good team coordination, if you annoy the whole enemy team at the right time that can lead to a team wipe. But even with a random team of pub players, a good distraction can allow the more objective-minded players an opening to slip through and contest the objective.
By the way, make sure there’s only one distraction and no more. There is no point in creating an opening for your team if only one or two players are left to contest the objective against half the enemy team.
As for which classes are the most effective distractions, there are three good choices. The Scout can get in and out of a fight quickly, and his Scattergun can deal a lot of damage. Not to mention, the Force-a-Nature and the Shortstop’s alt-fire can push someone out of position. And the Wrap Assassin’s and the Flying Guillotine’s bleed effect will really annoy people for some time as they scurry along trying to find a way to stop the bleeding. Pyro’s Airblast makes him the default class for pushing people off perches, cliffs and control points. Afterburn is annoying, but especially to Snipers, since that’ll affect their aim while scoped in, and it is very, very visible. Spy can be a wonderful distraction just by doing his job, and long-range Ambassador shots will really keep everyone on their toes.