As long I can remember, and I started really getting into baseball about 2005, the bench mark for a league average ratio has been 2.00. Anything below two, and the saber community would be skeptical of a pitchers ability to miss bats and keep runners off base. Anything above two, and that pitcher would have the confidence of the community. Of course, there are caveats and examples of cases where this doesn't hold, but generally it worked quite well as a measuring stick.
Nearing the end of 2012 however, the numbers tell a different story. The league average K/BB ratio has climbed over 22% in just three years - going from 2.02 in 2009 up to 2.47 in the current season. Clearly, something significant has happened. Here's the K/BB data over the past ten seasons (thanks to Baseball-Reference.com) :
I think by now, we all know that baseball's environment is quite different from ten years ago. However, I am suggesting that as a whole, expectations and reactions to results have not been adjusted adequately.
After finding these data, I thought the numbers may have been affected by the increased use by relievers. However, this is not the case, as starting pitchers have posted a superior ratio (2.51 K/BB) to that of relievers (2.41) this season.
In summary, as ERA's have gone down, strikeouts have increased and walks have gone down, we need to adjust not only our concept of the statistics themselves but they're impact on the baselines that are generally accepted.