It might be the biggest news to hit the Pacific Northwest since Mount St. Helens exploded.

Or not. But a lot of American League hitters, and especially those who play for the Seattle Mariners, were probably thrilled with Tuesday's news that Seattle's Safeco Field will be significantly more hitter-friendly in 2013. Or power-hitter-friendly, anyway. Because the fences are getting moved in this winter. Way in.

Here's the takeaway, via MLB.com's Greg Johns:

The biggest change involves the left-field power alley, which has been tough on right-handed hitters since the park opened in 1999.

The fence will be moved in from four to 17 feet at different points in left field and four feet from straight center field to the right-center gap. Additionally, the 16-foot-high hand-operated scoreboard down the left-field line will be moved back and no longer be part of the fence, so the outfield wall will be eight-feet high all the way around the park.

Distances directly down the lines will remain the same, so the changes primarily affect the power alleys in left-center and right-center.

This is huge, as Safeco becomes much less huge. From 2009 through '11 (at least), Safeco was one of the toughest parks in the American League for hitters, generally. And specifically, it was death on right-handed power hitters.

As Johns points out, this season the M's rank last in the American League in scoring ... but fourth in the league in road scoring, which is sort of a mind-blowing figure.

Of course, the tricky thing about changing your ballpark is that you never really know if you'll help your opponents more than you're helping yourself. The Mariners' hitters will undoubtedly have better numbers next season ... and their pitchers worse numbers. What you hope is that in the long term, having a more "fair" ballpark will help you develop young hitters and sign veterans, without unduly discouraging pitchers.

My personal opinion is that teams are best-served by pitcher's parks, but not so extreme that the hitters spend half their time bitching about it. We'll see how far the Mariners are taking this thing, in two or three years when we've got enough numbers.