SEATTLE - Tired of seeing fly balls die in a cavernous outfield and free-agent sluggers choose more hitter-friendly settings, the Seattle Mariners are bringing in the fences at Safeco Field.

The Mariners announced Tuesday they will move in the fences for the 2013 season after years of debate on the impact one of the more spacious outfields in baseball was having on their offense.

"It's all about just the ballpark playing fair and I think they've done a great job with the changes they are planning on making. I just think it's a win-win situation," Seattle manager Eric Wedge said. "I think it's fantastic for our younger position players, it's a more attractive location now for players outside the organization who might consider coming this direction, so I think it's a good decision."

The biggest change will come in the left-center field alley, where the fence will move in as much as 17 feet. The left-center power alley is currently 390 feet, but will be at 378 next season. From there, instead of a rounded fence, the wall will move straight out to its deepest point at 405 feet, four feet shorter than currently. The straighter line of the fence will lead to the 17-foot change.

Seattle general manager Jack Zduriencik said many factors were taken into account when determining whether changes to the field would be made, including Seattle's notoriously chilly April and May. A small group of Mariners front-office personnel were brought together in the spring to begin a study on whether the fences should be moved and where the dimensions should be. Led by assistant general manager Jeff Kingston, the group determined center field and left-center field were the areas most outside the norm.

"When we looked at the numbers in relation to the other 29 parks, those were the two areas that really stuck out. We felt like we needed to make an adjustment," Kingston said.

The left-field corner will also see a significant change, with the removal of the hand-operated scoreboard that raised the fence to 16 feet. The fence height will now be a uniform 8 feet from one foul pole to the other and the hand-operated scoreboard will be relocated to a yet-to-be-determined location.

The work on changing the dimensions is expected to begin soon after the conclusion of the season. The left-field and right-field lines are the only two listed dimensions that won't change. The deepest point in the park - just to the left of center field - will move in 4 feet to 405, while straightaway center will be 401. Right-center field will also come in 4 feet to 381.

"Our goal was to create an atmosphere here that wouldn't punish pitching but also make it a fair ballpark," Zduriencik said. "The dimensions the committee came up with and recommended are the dimensions that will accomplish that goal. We think the park will play fair."

This is the first change to the dimensions of the ballpark since it opened in 1999. Hitters have long complained of the cavernous dimensions in the outfield and the numbers show Safeco Field to be one of the more unfriendly parks for hitters in baseball. Pitchers love the vast outfield, and fly ball pitchers - like current Mariners starter Jason Vargas - have thrived throwing in Seattle.

“I don’t think you change the way you pitch based on the ballpark that you are in, especially when the dimensions aren’t going to change that much,” Vargas said. “It’s still going to be fair.”

Since 2000, the first full season for Safeco Field, the Mariners have scored the fewest runs and have the lowest batting average at home of any team in the American League. They are fourth-worst in baseball in home runs in their home park, but have the second-best team ERA in the AL at home during that span.

The decision was met by universal praise from Mariners hitters, who at times have acknowledged the mental tricks played on their minds after seeing a well-struck ball that would be a homer in nearly every park in baseball become a long flyout in Seattle.

“Being in the field and watching guys hit balls and seeing it die and being at home plate and seeing it — it is what it is right now,” Seattle first baseman Justin Smoak said. “It’s just one of those things where I think it will be a big confidence booster for everybody.”