I don't think we were far from a gem at all. Neither did the rest of the NFL world. We had a damn fine young offensive team put together that looked like they were going places. You're right that they were young, immature, and still needed to work through some kinks, but you're wrong to downplay the chemistry that they showed.
We're nowhere close to what we had last offseason, despite having most all of the same players on offense outside of Cutler and the new runningbacks.
Any way you want to look at it, we've regressed on offense - whether you want to agree with the consensus that we had a young and rising offense last year or not.