That offense has heated in recent weeks, helped by Trumbo's increased presence behind the middle-of-the-order group of Kyle Seager, Nelson Cruz and Robinson Cano.
"It feels all right," Trumbo said. "It feels like there's a lot more in the tank, but sometimes you have to kind of be happy with what you've done. I'm glad the power is showing up a little more here and there, but I think there's still quite a bit of room for improvement."
The 29-year-old has a career line of .248/.297/.455 in six seasons in the Majors. Despite his frigid start, he's up to .240/.289/.352 with Seattle and trending the right direction.
"He's swinging the bat pretty decent," manager Lloyd McClendon said. "He's been a lot more consistent, he's starting to drive the ball better. He's getting his doubles and starting to hit some home runs. It's good to see."
Trumbo always has had success against Rangers lefty Derek Holland. Wednesday's home run was his fifth off Holland in 41 career at-bats, the most by any big league hitter against the Texas veteran. Yoenis Cespedes has gone deep off Holland four times.
But Trumbo is hitting better against all comers at the moment and is definitely a part of the reason the Mariners' offense has upgraded considerably in the second half, leading the Majors in extra-base hits since the All-Star break while posting the second-highest OPS.
Trumbo says he's happy to have dug himself out of the hole created by his slow start.
"No doubt," he said. "I think the first month I was here it was pretty poor. But if you'd take it in segments, I think the last month has looked a lot better. It goes in waves. The overall numbers are maybe not quite what I'd like, but a tad closer to what I want to do.
"It would be nice to get on a big run, but we'll take what we can get. As long as the at-bats are quality, it's positive."
Greg Johns is a reporter for MLB.com. Follow him on Twitter @GregJohnsMLB, read his Mariners Musings blog, and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.