Jaso came to Seattle from Tampa Bay with a reputation as a good on-base guy, but he's hitting with more pop this season. His .471 slugging percentage is well above his .365 average in three seasons with the Rays, where he totaled 10 home runs in 203 games.
His current slugging percentage is the highest of any Mariners player as he's added 13 doubles and two triples in just 187 at-bats. Manager Eric Wedge turned him loose with a 3-0 count against Ervin Santana on Friday and he responded with the three-run blast.
"Give him the green light 3-0 and that's what you're supposed to do, turn it around like that," Wedge said. "Or if you're going to miss it, miss it pull-side. It was nice to see how aggressive he was with it.
"He has some power. He's shown that at times. I don't think that's by far the biggest part of his game. He's a line-drive type who can drive the gap or hit one out on occasion."
Wedge has been giving Jaso increased playing time as the season has progressed, including more duties behind the plate in recent weeks.
"He's called a good game," Wedge said. "He has a good feel back there. He's moving around well. He has an air of confidence to him, which I like."