Given that the fences from left field to right-center are being moved closer and the left field wall will be made shorter, we can predict with some certainty that Safeco Field will be more hitter friendly in 2013, particularly for right-handed sluggers. The bigger question is the degree of difference it will make for said hitters-- a question that can't be easily answered until we begin to see it in realtime.
For all we know the changes being made beyond the new walls or even up around the new video board could alter the airflow in and out of Safeco, triggering changes previously unconsidered. Given that we've heard of hitters allowing the formerly cavernous outfield to wreak havoc in their minds, a more likely factor could be how hitters change the way they think. Maybe they will play with more confidence. Maybe they will be less likely to try and alter their gameplan against their strengths. Maybe they will be more focused with one less thing to worry about. Then again, wouldn't pitchers tweak a few things as well?
We'll find out if those and other factors come into play soon enough. For now, the simplest way to speculate on the possible effect is to ignore the tricky stuff and take a gander at hit charts to see what might have been.
"Simple" is the key word. Again, we don't know if a fly ball from 2012 will cut through the air in the exact same way in 2013. More importantly, the deep flies hit by a player one year aren't indicative of what he might do the next. The sample sizes are minuscule.
With those caveats in mind, let's take a quick look at how Seattle's most lauded right-handed masher might have faired had Safeco's changes happened ahead of the 2012 season.
Jesus Montero hit .260/.298/.386 with 15 home runs, a disappointing line given the expectations he faced in pinstripes. Lucky for him, Safeco Field absorbed much of the blame as his home/road splits told very different stories. His .227/.268/.337 line at home painted the picture of a flop, the latest to be overrated by the frenzied New York hype machine. His .295/.330/.438 line on the road showed a rookie who more than held his own at just 22 years old.
If he had performed at home as he did on the road, how would that adjust our impression of the Seattle Mariners' rebuild?
Unfortunately, having the fences shortened a year early probably wouldn't have leveled out Montero's performance. The dimensions and atmospheric conditions still point towards Safeco being somewhat unkind to right-handed hitters, and Montero's 2012 hit chart compared to the new dimensions does nothing to dispute that expectation.
Montero appears to have hit four balls at Safeco in 2012 that went far enough to clear the new fences. One was recorded as an out while the others went for hits, presumably of the extra-base variety. Adding the four home runs we get the following season line from Montero:
.262/.302/.402 with 19 home runs.
Still not "the next Manny Ramirez," still one of the worst catcher lines of 2012 from a guy that's supposed to provide most of his value through offense. The four added home runs (and three subtracted doubles) do not restore all of Montero's shine. The abysmal home line ticks up from .227/.268/.337 to a still embarrassing .231/.271/.375, and getting generous and imagining a couple extra doubles due to outfielders contending with the new walls does little to improve his standing.
Again, the effect could certainly be greater than what is observed here with Montero. The point is simply that while the fences coming in should be helpful to some players, expectations should probably be tempered. The new dimensions won't be turning anyone into a world beater.
Just don't tell any curious free agents.
Want to Feel Better About Jesus Montero?
Core Growth Required
Guti at the Track: A Tribute