The Mariners have officially agreed to a contract with right-hander Tom Wilhelmsen, as Bob Dutton of the Tacoma News Tribune first reported. It’s a one-year, major league deal for the veteran reliever.

Seattle expects to keep Wilhelmsen on the major league roster for two days before optioning him to Triple-A, per the report, as the club needs to add a starter for Friday. He’ll need to clear waivers, but that’s generally an easy procedural barrier to clear — all the more so in this case, since any team could have signed him.

[Related: Updated Mariners depth chart]

Wilhelmsen had never suited up for a major league team other than the Mariners prior to his trade to the Rangers this winter. Things never took in Texas, however, as he surrendered 25 earned runs on 38 hits (with an 11:9 K/BB ratio) over his 21 1/3 frames. Wilhelmsen ultimately chose to give up about $1.8MM — the remainder of his $3.1MM arbitration deal — by declining an assignment after being outrighted.

That was a far cry from the work that Wilhelmsen put in with the M’s. Over five seasons in Seattle, he contributed 312 1/3 innings of 2.97 ERA pitching, with 8.5 K/9 against 4.0 BB/9. Working off of a fastball sitting at 95, his slider and curve drove a swinging strike rate that consistently ran into the double digits.

Since swapping sides in the AL West, Wilhelmsen lost nearly a full tick on his heater and stepped back to a 9.4% whiff rate. That looks more like an erosion than a collapse but he also saw a big jump in contact on pitches in the zone (93.5%) and allowed hard contact at a rate (39.1%) nearly double his marks from the prior two seasons. The result was a sky-high 24.1% home run-per-flyball rate and a .388 batting average on balls in play.

Seattle will obviously hope that Wilhelmsen can return to being the productive bullpen piece that he once was, but it will take some tinkering to do so. A glance at his Brooks Baseball profile suggests that the stuff is still largely intact, so it’s certainly possible to imagine a turnaround. Anyway, it’s pretty much all upside at this point. The club has enjoyed quality production from the primary player he was traded for, Leonys Martin, so that deal has already worked out quite nicely for GM Jerry Dipoto.