If the numbers keep heading in this direction, there will eventually be more pitchers in this group than out of it. The number of pitchers in this group has skyrocketed for both starters and relievers, but the bulk of the increase obviously has come from relievers. This is becoming like hitting 20 home runs was during the steroid era for a position player. What was once something done only by elite players is now expected of pretty much everyone.
It's not very surprising that there are more pitchers with high strikeout numbers. As bullpens are staffed with more young fireballers than old retreads, it make sense that there would more high-strikeout pitchers. It's a little surprising, though, that their walk totals have been going down as well. The steroid testing has probably helped pitchers in several different ways.
The hitters aren't putting up the same numbers and the pitchers aren't intimidated. More and more young pitchers are like what we saw Trevor Rosenthal do in the postseason. They throw their heat over the plate and dare the hitters to make contact. The increase in the number of pitchers with high strikeout and low walk totals over the past ten years has been astonishing and it might not be stopping anytime soon.