The number of California wines flawed by apparent cork taint (2,4,6-trichloroanisole, otherwise known as TCA) fell in 2012 to its lowest level since we started informally tracking this controversial issue in 2005.

Roughly 3.7 percent of the 3,269 cork-sealed wines from California that we tasted in the Wine Spectator office in 2012 were thought to be tainted by a bad cork. It's not a scientific study, since we don't test the corks or wines to determine the cause. Yet the Wine Spectator editors who review California wines keep track of how many we think have an obvious TCA character. Many other wines may taste off as well, though it's less clear why. Our bottom line is, any wine thought to be off for whatever reason is automatically retasted. Of note, nearly 300 of the California wines we tasted in 2012 were sealed with twist-off closures.

That the percentage of TCA-tainted wines in 2012 is the lowest we've seen (down from 3.8 percent in 2011; the highest level coming in 2007 at 9.5 percent, or a 1-bottle-per-case average), it presents both a case for those who claim cork quality has improved (as it would appear) and that there is still a problem. Many of us believe no wine should be tainted by a bad cork; most of those who subscribe to that advocate alternatives, primarily the twist-off closure, or screw cap, but there are numerous alternatives.

TCA-taint, though, is only one of cork's problems, as I was reminded over the holidays. A friend asked me to bring some mature wines to a dinner this past week. All four of the older wines (including a charming 1981 Opus One and a potent 2001 Schrader Cabernet) had their corks either split in half or crumble as they were removed (even using an ah-so). The 2001 Paloma Merlot was corked, undrinkable.

The question becomes, is the 3.7 percent cork taint a victory for corks, or a reminder that there is still room for improvement, if not near perfection? Or is it a non-issue?