One of the biggest offseason deals so far has been the Seattle Mariners acquiring center fielder Leonys Martin from the Texas Rangers. The Mariners were in desperate need of a defensive upgrade in center and Martin had fallen out of favor with the Rangers after struggling with injuries and the bat in 2015. With the emergence of Delino DeShields in center, plus Nomar Mazara on the way, there wasn't room for Martin in a crowded Texas outfield and he was a non-tender candidate.

Mariners GM Jerry Dipoto pounced quickly in the offseason, getting Martin for reliever Tom Wilhelmsen and corner infield prospect Patrick Kivlehan. Wilhelmsen is back in Triple-A after posting a 9.98 ERA and surrendering six home runs in 15.1 innings and Kivlehan is hitting .184 for Round Rock.

Martin, meanwhile, has played his usual above-average defense (plus-4 defensive runs saved), but the big bonus has been with the bat, where he's been red hot in May. Tuesday night he did this:

That capped a big comeback by the Mariners. Robinson Cano hit a two-run homer in the eighth and then Martin hit the walk-off to give them a 6-5 win over the A's. I love the Mariners' announcers, with Jay Buhner cackling in delight as the ball sailed way beyond the outfield. A's closer Ryan Madson threw four straight changeups to Martin. The first three were good, low or low and away, but the fourth one was a cookie, as bad a pitch as you can make:

What a game. Wow @leonys27martin ! Doin it! Can't sleep that was awesome. Great team win there #bloopandablast #GoMariners — Steve Cishek (@srSHREK31) May 25, 2016

Martin is now hitting .259/.337/.483 with a career-high nine home runs and ranks in the top 25 among AL position players in WAR. For the Rangers, the trade has been extra painful because Martin is helping a division rival -- a team they're currently battling for first place.

Jason Churchill of ProspectInsider.com had a great review of Martin's new approach at the plate a couple of days ago and points out reasons to believe in his new power stroke. Martin has raised his hands in his set-up, helping him erase a trigger motion that created a longer swing and inconsistent path to the ball. Jason writes:

In 2016, Martin’s bat is at an angle more consistent with the kind of trajectory that produces hard-hit line drives and fly balls, and the barrel, while still somewhat pointed toward the pitcher, is much more ideally angled, too. He still waggles it toward the pitcher pre-pitch sometimes, which ideally will go away altogether, eventually. We’ve heard Mike Blowers comment on the Root Sports Broadcast about the bat wrap and that Edgar Martinez has been working with Martin on that very thing. The hands are in a better position to trigger the swing, the bat head is in a better spot to be sent to attack the pitch and the bat angle helps Martin create a more consistent and healthier bat path (swing plane). The swing itself is a bit shorter, too, which can help with contact and consistency. I also have noticed he’s setting up a little more closed at the feet, hip and shoulder than he was a year ago. It’s not easily noticed by the naked eye, but it’s there and part of his set of adjustments this seasons.

Martin is striking out more, but has replaced that with a few more walks and more power. His fly ball rate has increased from 28 percent to 38 percent. The Mariners are nine games over .500 and third in the AL in runs per game. Martin has been a big reason why.