My guess is that this is where a good bit of the talk about the Year of the Pitcher comes from. An especially large cohort of quality young hurlers who weren't on center stage a few years ago -- not just high-strikeout pitchers 25 and under, mind you -- is tasting success at a time when scoring is returning to levels not seen in almost two decades and strikeout rates are at an all-time high. Other changes in the game may be contributing to both trends, but they're the faces of the phenomenon, this so-called Year of the Pitcher.
I'm glad Jaffe threw in that bit about "other changes in the game" because this probably isn't a simple thing. One change that doesn't generally show up in these discussions is, potentially, a big one: defense. There's a general impression that teams are focusing more on defense, in part because fielding is more cost-effective than hitting. Obviously, if teams are employing better fielders, fewer batted balls will become hits ... but there's more right?
If you're selecting for defense, you're taking runs away from your opponents and you're taking runs away from yourself. It's a two-fer.
Granted, we can make too much of this. When I look at lists of the best fielders at each position, I see a lot of guys who hit pretty well and would be in the lineup even if they weren't sterling defenders. But teams are paying more attention to defense; more to the point, they're paying attention to defense in a more systematic (and yes, intelligent) way, and they're probably slightly more willing to trade offense for defense. Which, again, will lead to run prevention on both sides of the team ledger.
And again, we're not really putting the pieces together yet. But we've got most of them on the table, I think.