Jan 08, 2010 4:54 PM EST

The Mariners and center fielder Franklin Gutierrez have agreed to terms on a four-year, $20.5 million extension.

The deal allows Gutierrez to avoid arbitration.

He hit .283 with 18 homers and 70 RBIs last season, his first in Seattle, and the deal includes a club option for the 2014 season.

"Franklin had a breakthrough season last year," Mariners general manager Jack Zduriencik said. "But the exciting thing for us is that we believe he will only continue to get better. We feel he was the best defensive center fielder in the American League last year, and he was a huge part of the success of our pitching staff leading the AL in ERA. Offensively, his combination of speed and power is a perfect fit for our club -- and he is an outstanding person."

Via ESPN