Remember when you first saw the Power Rangers? They were awesome! Five cool kids who could, at will, morph into totally wicked evil-fighting colourful superheroes! Over time, the shows got better (relatively speaking, at least). There was a bit more depth, a bit more character development, the bad guys got more complex... the Power Rangers were moving up in the world.
Then you had better things to do. You missed a few shows, you went away for a while, and then it all went pear shaped. Next time you looked, there were eight power rangers, they could morph into dinosaurs and donkeys and spaceships, the plotlines became more and more convoluted. It went bad.
And this, give or take a few bad special effects and poorly dubbed action scenes, is precisely what happens to wine. At first, a good red will be quite straightforward: it's made from fruit, so the main flavours you'll taste will be- wait for it- fruity. Plums and berries and shiny red cherries. There will also be some tannins- these come from the skin of the grapes, from the stems and seeds and all the woody, non-flesh parts of the grape. The word the wine people use for the tannin taste in a young wine is 'astringent'- kinda like a dry, puckery sensation.
Over time, like their colleagues running Power Rangers, these tannins will improve things. The fruity flavours will remain, but will be embellished by the rich, smoky, earthy, woody flavours imparted by the tannins. This is why it's good to age some wines. They taste better and better over the years, because the tannins add more of this richness to balance out the fruit, and the final product can be amazing. When these tannins are done adding flavour they'll drop out of the wine as sediment and collect on the bottom of the bottle. This is why it's necessary to decant older wines before serving them.
The problem is that you can leave your precious wine a bit too long, wait for it to grow a bit too much, and then when you finally do open it you'll fine the bottled equivalent of Power Rangers: Dino Thunder, with mechanical triceratops that fire lasers out of their horns. This is what people in the industry call 'not good'. Instead of the nuanced and complex balance of finely interlaced flavours, you just get a mouthful of wet cardboard. The wine will look brown, not red, and it'll have a tart, vinegar-esque aspect to it. There will still be some flavour kicking around, but it will be some soggy relic of what it once was. Think about biting into an apple to find a powdery mush instead of crisp juicyness.
So there's no point trying to drink every bottle of wine at the very peak of its development. If you always drink a bottle too young, you're never going to be disappointed. I just wish I could say the same for Power Rangers.