Seager, 24, is now batting .353 (6-for-17) with four RBIs and five runs in six games. He came to camp with a slightly shortened swing designed to help provide more power, and the results have been promising to date.
His fifth-inning home run sailed over the center-field fence at the 410-foot mark, coming on a 1-0 pitch from former Mariners reliever Jamey Wright.
"That was very similar to the ball he hit a few days back," manager Eric Wedge said, referring to Seager's first home run last Sunday against the Padres. "It's just a good sound off the bat and he's back-spinning the ball and it's going a long way.
"He's definitely stronger and he barrels up the ball very well for a young man. He's driving it more this spring."
The Mariners have hit 13 home runs in their first nine Cactus League games.
"We're seeing some good things," said Wedge. "We need to see more of it. But I like to see what we're seeing in terms of the progress."