IGN's RPG Vault asked 15 Bethesda employees what they did on Oblivion and what they were most proud of. This must be one of those hard hitting pieces of gaming journalism we keep on hearing about... honest to god, we've had handjobs rougher than this "interview." Nevertheless, RPG Vault did manage to drudge up some real corkers. From Bruce Nesmith, designer:

I was responsible for a lot of the game balance in Oblivion, both for monsters and for the economy. In virtually every game in every genre, game balance is considered to be one of the trickiest things to do well. I succeeded beyond my hopes and expectations, particularly for a game of the enormous scope and complexity of Oblivion.

Ha ha! Yeah, no, really... great job there, Bruce. The monster leveling system in Oblivion feels like you guys "designed" it on the back of a cocktail napkin at the beginning of the project, just programmed it in and then never actually bothered to see how it played. The main quest can become almost impossible to complete if you stumble off of it for a long enough time, forcing you to game the system. Oblivion's a fun game, but balanced? No.

The Elder Scrolls IV: Oblivion Team Q&A #1 [RPG Vault]