Yah so I've been playing a lot of ranked games recently, and I've noticed something.

Carrying as a champion with a truckload of CC is a lot easier than carrying with your standard top/ap/ad carry. Also, supports and junglers carry harder than any other role.

To explain this I'm going to take my new 'free elo' champions. My old free elo champion was Kennen in mid/top. Yet I've lost a large portion of those games, all because of one thing: I was a squishy carry.

My new 'free elo' champions are Nautilus, Alistar, and Malphite. They all have something in common, and that is the ability to EASILY shut down the enemy AD Carry, and also to potentially get your own AD Carry insanely fed. For each of these champions I either fill a support/supportish role or jungle.

Their core items are Heart of Gold and philosopher's stone, and Glacial Shroud/ Aegis of the Legion are also great items. This means they can build Randuin's Omen and Frozen Heart without really altering their optimal build choices. This effectively shuts down the enemy AD Carry by reducing their attack speed by 48% (it stacks multiplicatively), meaning all the AD/Attack Speed/even ARMOR PEN ( Last Whisper) won't help them. That's their first way of shutting down the other AD Carry (wait, there's more~)

They each have an insane amount of CC that will GUARANTEE death if your team is paying even a brain cell's worth of attention. Naut has a targetted 2 second knockup, while clearing a path for your team to move in. Master Ali's combo and you essentially have a gap closing knockup, or you can always Flash Q W and disposition them right into your team. Malph IGNORES ALL CC and blows up the other team, then adds another 50% debuff to their attack speed while sticking onto them with Q.

Lastly, they have the tankiness at a very EARLY LEVEL (even level 2. That was insane.) to tower dive, and potentially hold an oracles elixir. That means at early levels you can dive and kill them over and over and they CANNOT DO ANYTHING ABOUT IT. Wanna ward? I buy an Oracle's Elixir. Wanna tower hug? You get dived and the turret won't kill me fast enough. This will easily net your OWN AD Carry multiple kills and therefore winning the game.

Why can't you do this as an AP Carry, or a hyper carry top like Riven or Jax? The answer is simple. No matter how tanky you feel or want to be, if you're building damage you WILL BE squishy and you WILL GET MELTED under focus. Tanks are unlike this, they *can* survive under relatively long durations of focus fire while destroying the other team's carries through massive CC. Another reason is that the best items/mechanics to counter a fed AD Carry is an Attack Speed debuff, NOT armor because they're going to buy a Last Whisper anyway and make your pathetic 150 armor obsolete.

Now, before you go off saying "This only happens in perfect games!" or "You're too reliant on your team to do damage!" let me tell you this:

This only happens in perfect games.
No it doesn't. All it takes is ONE teamfight, or ONE perfect Tibbers stun, ONE perfect Petrifying Gaze to change the game. The whole purpose of carrying yourself out of your so called Elo Hell is to prove you don't belong there, so there are TONS of chances to make that perfect ultimate count.

You're too reliant on your team to do damage.
Fed tanks still do damage! Ever heard of Trinity Tanks? How about Wit's End? Both are great items that do tremendous amounts of damage if built correctly. Also, there are tons of items like Abyssal Mask (which supplies both a chunk of damage and survivability) or skills like Runic Skin/ Ground Slam that scale directly off being tanky. Not to mention you can dive towers more and more easily. That being said, fed tanks are in a way SCARIER than that fed Vayne or Graves.

Oh, you're also unkillable to the point where you can have your team take kills while you afk in the middle of their team making tea. Those who say tanks don't snowball as well probably think AD Carries have the highest chance to win games.

So, to wrap this up, the best carries in mid-low elo are high CC tanks who can directly get their own carries fed. Carries are easily shut down with constant disruption in both team fights and during the lane phase, while tanks are more resilient with relatively better recovery because of gp5. So next time you see someone instalock Anivia or Vayne and tank your 'hyper carry' position, pick a champion like Blitzcrank or Malphite and indirectly carry that game ;)