I had always understood that a wine, once bottled, would improve in taste as the tannins and acids mellowed over time in the bottle. This would happen until a peak was reached and the then any depth of flavors held in the wine would shallow out, until it was no longer drinkable. Well I had the interesting experience the other day to try an '06 Bressler Napa cab that had been held back in distribution due it’s perceived shallowness. The wine was no longer shallow, but quite rich in it’s flavors of light pepper, chocolate, and cranberry. After speaking with Bob Bressler I learned that some wines will actually vary over time with the flavors becoming more robust and then subsiding and back and forth over a few years.
After the discussion with Bob I went through my mind (what little mind I have these days) over my experience with some of the wines I have in my collection and found that this in dead was how many of my wines have performed. 6 months or a year ago I opened a somewhat expensive bottle of Napa Cab that was not as deep or tasty as when I originally purchased it. However, just recently I opened another bottle that was spectacular in depth and taste. While I was feeling like I was let down by my purchase and almost ready to give up on that vintage, here it came back screaming at me to drink it.
So I guess one has to be patient with your wine, because if it seems poor today, maybe tomorrow it will be better.