The Mariners needed a center fielder after they sent Brad Miller and Austin Jackson packing over the past year. They had an extra reliever, maybe, after they acquired Joaquin Benoit from the Padres last week. And, even given all the flaws in their new (probably platoon) center fielder, it’s hard not to like such a low-risk, high-reward move. Even if you value relievers highly.

But these are the things you have to talk about when you try to evaluate the trade that sent center fielder Leonys Martin and reliever Anthony Bass to the Mariners and reliever Tom Wilhelmsen and outfielder James Jones to the Rangers.

First, the newcomer: Leonys Martin. His original contract (three years and $15.5 million) is expired, and he’s now under the Mariners’ control for three years. Given how badly his season went last year — Martin was the sixth-worst bat in baseball this year — he may not cost that much. MLBTradeRumors, using Matt Swartz’s arbitration projection work, has him down for $1.6 million this year. Tom Wilhelmsen, the pitcher they sent the Rangers, will cost $3.0 million this year.

Wins Above Replacement says that the reliever, coming off of his second-best year, was roughly equivalent to the position player, coming off of his worst season.

But that sort of analysis supposes one thing: that Martin will be good enough to continue getting 300+ plate appearances a year going forward. If his bat doesn’t improve, then all the defense in the world won’t keep him on the field in order to accrue that value.

In that case, a reliable reliever would be more valuable. Wilhelmsen seems that way, since he’s struck out nearly a batter per inning and kept his ERA near 3.0 in three out of the four years he’s been in the league.

But is it consistency without excellence? Wilhelmsen has the 106th best strikeout rate among qualified relievers since 2012. But! If you up the limit to 250 innings pitched, he zooms up the list to 14th in strikeout rate. Sitting between Kelvin Herrera and Luke Gregerson is a nice spot. It’s even better by velocity, where he’s fifth.

There are only 23 relievers that have thrown 250 innings since 2012, though. And though past good health is a good sign for future good health, putting your stock in this list of relievers to continue being healthy because they’ve been healthy for 250 innings so far seems like folly.

Either way, on that list sits Joaquin Benoit, who has had a better strikeout rate and better walk rate than Wilhelmsen over the same time period. The Mariners didn’t have an elite reliever either way, and may have felt they had some surplus between the two. Even if Benoit can’t do this.

If Martin can hit enough to stay on the field, even in a platoon role, he should easily outproduce Wilhelmsen. His defense has been top five by UZR/150, DRS, and highlight-reel throws and leaps over the last three years.

So what happened to Martin’s bat last year? He hit career full-year worsts in walk rate, strikeout rate, ground-ball rate, hard-hit rate, soft-hit rate, line drive rate, swinging strike rate, and zone-swing rate. He couldn’t discern balls and strikes, got tentative and stopped swinging at strikes, and didn’t put the ball in play with any authority. In short, everything went wrong.

Asking him to bounce back from last year’s work to his Steamer-projected line is not actually asking a lot. That 29-point swing in weighted offense, paired with his 39-point drop the year before, would bring his total bounce to 68 points, or 144th-biggest in baseball since 1974. That bounce would be on par with what Jose Altuve did in 2014 after a poor 2013, for example. Getting the guy before the bounce-back seems ideal, and the Mariners’ Jerry Dipoto admitted as much to Ryan Divish Monday.

There isn’t a huge red flag in Martin’s batting line, other than he’s never been that good at the plate. He saw a few more fastballs last year and swung at them less, but at 28, it seems a little early to be worried about declining bat speed on the level that would finish a career. He didn’t whiff a lot more on any one pitch type — just a little more on all types.

Martin did lose a hot zone on the inside part of the plate that he enjoyed in 2014, and he did reach and swing less than he ever had before. Perhaps he just needs to be aggressive, take his lumps, and do a bit of damage on the pitches that he can handle. Not everyone is built to be disciplined at the plate.

If you’re asking the 28-year-old Leonys Martin to be decent at the plate and good with the glove, you’re not actually asking too much. Bounce backs like this have happened very often, and he’s young enough to believe he can find a little something at the plate. He’s not good against lefties, but he can solve two thirds of your center field situation, most likely.

On the other hand, Tom Wilhelmsen has put up a resume of his own. It’s not his baseball fault that “The Bartender” is 31 — he spent some time outside of the sport finding himself, and since he’s been back, he’s used his big fastball and power curve to strike guys out reliably. Still, his best foot forward is volume, and that’s a strange note to strike for a reliever, given they contribute less in volume than any other position.

Maybe this was all about team needs. With Delino Deshields here, and Lewis Brinson in the wings, the Rangers probably have center field figured out, to some extent. Jones can be a backup plan, too.

The Rangers haven’t spent a ton of assets acquiring the relievers they have, but now with Sam Dyson‘s Britton-esque sinker, Keone Kela‘s power arsenal, and Shawn Tolleson’s starting pitcher mix, they have another power arm at the back end of their bullpen.

And with a limited payroll to work with, it seems that Dipoto prefers to go and find more relievers than try to sign a center fielder. After all, he talked about being a run-prevention team, and he just acquired the best defensive center fielder they’ve seen in a while in Seattle.