First off, i'm relatively new to this game, i'm not doing anything ranked or serious, and i'm normally not playing 5v5 matches. I decided to do one however, where I kicked ass pretty hard as Ahri. Got first blood. Ended up going 18 - 2 - 16. Meanwhile on their team, their Volibear went 2 - 19 and had a 6 - 12 Veigar. We got Baron every time he was up, and at one point our team was something like 35 kills 7 deaths. But then the enemy team just somehow champed through a TON of kills, in 5v5 team fights even though our team was fed hard.

How?

http://imageshack.us/f/12/lolwtfdefeat.png/

They ended up winning.

I go. 0/0/0 for 20-25 minutes. Farming. Staying alive. Harassing.

Maybe get to 1/0/0 or 2/0/0

At some point though. Unless the enemy has been fed, badly, I can start cleaning up. Going 1vs2/3 and when im not countered with thornmail or a real tank I can go 2vs5 and be done in 12 seconds.

Some team comps rely on this. Kill em early. Stick together. Deny them farm.

You will lose if the game drags on.

Ill elaborate.

If you have a carry in mid and go in.to gank, always let the carry make the kill id possible.

Snowball effect.

They won because they got what mattered, the towers and ultimately the nexus.

Though with their team makeup I'de be a bit peeved at that loss lol.

We pushed more towers than they did. :/

Not only that, but I can't understand how they got ANY gear at all with all of our harassing.

45 minute game...
no huge disparity in minion kills...
both teams full of glass cannons...

Their team -- has stronger "Glass cannons", champions with some innate durability, whereas yours only has Xin to fill that slot.

They have significant AoE damage output (Volibear ult, Wukong ult, Sivir Ricochet, Renektons Q and Ult, Veigars stun), while you have 5 dueling type champions (single target focus ideal).

They have a variety of CC (an AoE stun, a single target stun, AoE knockup, AoE slow+damage, Throw) while you have...1 single target knock up, 1 single target taunt, 1 single target snare, and 1 single target fear.

Looking at their scores, their Volibear performed poorly...but...this is really simple -- they had more heal, sustain, overall output capability in teamfights, better CC, and they wised up enough that they took the late game teamfights. Late game deaths matter much more than early game ones, especially in a game of that length where gold will accumulate, especially if towers are going down. They had 3 semi tanks, you had 1 -- in a sustained fight/long game, they win. You drew the match out too long, and didn't take the advantage while you had it.

It only takes one bad teamfight at the wrong time to lose a game. So sounds like that is what happened.

You had a very squishy team, when your tanky characters are Nocturne and Xin it doesn't surprise me that you lost team fights.

Their Wukong and Renek were very geared out. When you get an advantage you need to use that...the longer you let the game drag on the better a chance they have to climb back into it.

They had less kills, but more assists, indicating that by the end of the game they were probably doing a little better teamwork at least in team fights. Volibear had a lot of deaths, but if he was tanking for them that's really a non-issue because any damage you do to him is damage you're not doing to his more dangerous team-mates.

Others have mentioned team comp already, and I think that's what it boils down to. If games go long, having no real tank hurts a TON. On top of having no tank, you and Yi were the only ones who built anything in the way of survivability, and only marginal amounts. Numerous times my team has been getting roflstomped by a high damage team early, but we all just said "they have no tank. If we survive for 20 minutes and get a little farm we win." And 90% of the time that's exactly how it pans out.

Yeah I played a game just like this recently.
The othr team had more kills, towers, minions, assits basically more of everything. But they didnt have a tank so it only took us 1 teamfight which we won becuase they focused amumu and they surrednered as we would have taken their nexus anyway.