The Seattle Mariners announced Tuesday they will move in the fences at their spacious park, Safeco Field, beginning next season. With the announcement, Safeco -- long known as a pitcher-friendly venue -- will undergo the first changes to its playing dimensions since it opened in 1999. The most noticeable improvement for hitters will be in the left-center field power alley, which will see a 12-foot reduction, from 390 feet to 378 feet. Another 4 feet will be shaved elsewhere along the alley, while straightaway center will decline from 405 to 401 feet, The Seattle Times reported. A hand-operated scoreboard in left field will be removed, shortening the height of the fence in the corner from 16 to 8 feet. \"Our goal was to create an environment that is fair for both hitters and pitchers,\" Mariners General Manager Jack Zduriencik said. \"Considering the current field dimensions as well as the climate in and around Safeco Field, we feel this will be accomplished with this new layout.\"