Well, for starters:
AD Annie doesn't scale well into late game, because of her base and per level Attack Speed (especially attack speed) and Attack Damage.
For comparison her AA DPS with items like in your game and Level 14 was 423 Dmg per second on average. Graves with the same items and level would have 525 dmg per second on average. This is quite a difference with Graves dealing 24% more damage than Annie - and Graves have an actual AD scalings and steroids (which I didn't even include here).
It's not like I mind using uncommon picks in normal game, but Annie adc is really not working due to base stats (the only thing she has going for her is high range), especially base attack speed (which, if you didn't know, affects all attack speed item purchases, making them significantly weaker on Annie than on other champions).
The other thing that your team was doing worse than enemies was warding. You guys didn't even had a sightstone. And vision is more important than even in League of Dragons (seriously, the games lately were often decided by who took more Dragons), and enemy Warwick took 3 of them. Do not underestimate the bonuses it gives. Even though you might have had a money advantage I wouldn't be surprised if they had actual stat advantage thanks to the Dragon buff.
And the last thing - they had slightly better teamfighting with Wukong and Leona combo, which helped too.
As for Warwick - I do believe that he needs some tweaks (or the new jungler items do), but this game wasn't lost because of that.