Richie Sexson was batting .218 with a .315 on-base percentage this season for the Mariners. (Elaine Thompson/Associated Press)

The last-place Seattle Mariners released Richie Sexson on Thursday, swallowing the remainder of the free-swinging slugger's big contract in the process.

Seattle also placed opening-day starter Erik Bedard on the 15-day disabled list with stiffness in his throwing shoulder, another blow to a team that expected to contend for the American League West title this season.

Bedard's move to the DL is retroactive to July 5, meaning the Navan, Ont., native will be eligible to return on July 20 — just 11 days before the July 31 non-waiver trade deadline.

The Mariners may wish to shop Bedard, 29, who has been unspectacular since being acquired in an off-season deal that sent top outfield prospect Adam Jones to Baltimore.

The left-hander is 6-4 with a 3.67 earned-run average and 72 strikeouts in 81 innings this season. Last year with the Orioles, he earned consideration for the AL Cy Young by going 13-5 with a 3.16 ERA and 221 strikeouts in 182 innings before a strained oblique ended his season in late August.

Injuries have plagued Bedard again this season. A sore hip landed him on the DL in April, and he complained of tightness in his left shoulder after his start against Detroit last Friday, when he went five innings and gave up one run, and left after throwing 99 pitches.

Sexson untradeable

The 33-year-old Sexson was batting .218 with a .315 on-base percentage and 11 home runs in 74 games this season for Seattle (36-55), which had the worst record in the American League entering Thursday's action.

The Brush Prairie, Wash., native also struck out 76 times in 252 at bats as she struggled to recapture the form that saw him hit a combined 73 home runs in 2005 and 2006, his first two seasons after leaving Arizona for a four-year, $50 million US contract with the Mariners.

Sexson, who hit a career-worst .205 with 21 homers and 100 strikeouts in '07, has often been benched this season in favour of the light-hitting and seldom-used Miguel Cairo.

"I think we gave Richie a lot of rope… and there just wasn't enough improvement," said Mariners interim general manager Lee Pelekoudas.

The Mariners would have loved to have been able to trade Sexson, but his $14 million salary this season made that nearly impossible. So now Seattle is eating the rest of that money in what may be the first of multiple moves to rid the last-place team of underperforming veterans.

Bolstered by a player payroll of $117 million, the Mariners expected to reach their first post-season since 2001. Instead they entered Thursday's game at Oakland 18 games out in the AL West.

Seattle has already fired general manager Bill Bavasi. Manager John McLaren and remains on track to become the first team with a $100 million payroll to lose 100 games.

With files from the Associated Press