The Seattle Seahawks gave their punter the boot Tuesday, added wide receiver Billy McMullen and may have another roster move to make Wednesday because right guard Rob Sims may have suffered a season-ending injury to his pectoral muscle. The Seahawks released Ryan Plackemeier, a seventh-round draft pick in 2006. They will replace him with former...

The Seahawks gave their punter the boot Tuesday, added wide receiver Billy McMullen and may have another roster move to make today because right guard Rob Sims may have suffered a season-ending injury to his pectoral muscle.

So much for the first off day of the regular season being idle.

The Seahawks released Ryan Plackemeier, a seventh-round draft pick in 2006. They will replace him with former Green Bay Packers punter Jon Ryan, who signed a two-year contract Tuesday with Seattle.

The Seahawks also released second-year receiver Jordan Kent and rookie running back Justin Forsett to make room on the 53-man roster for Jordan Babineaux and Rocky Bernard. Babineaux and Bernard were suspended by the NFL for Seattle’s opener.

Even bigger news could come today when the Seahawks are expected to put Sims on injured reserve because of a torn pectoral muscle. KJR-AM first reported the injury. The Seahawks did not confirm or deny it. If Sims does have a torn pectoral muscle, he would require surgery and be placed on injured reserve, ending his season.

Sims started at left guard last season and moved to the right side after the team signed Mike Wahle in the offseason. Seattle’s interior line struggled in Buffalo as the Bills finished with five sacks and held Seattle to 11 yards rushing in the first half.

If Sims is out, Floyd Womack is expected to be the first choice to become the starter at right guard. Mansfield Wrotto, a second-year lineman, played right guard throughout training camp.

Ryan, 26, averaged 44.5 yards per punt in two seasons with the Packers. Ryan’s career net average of 37 yards is more than a yard better than Plackemeier’s, not including Sunday’s loss in which Plackemeier averaged 30 yards in net punting and had a pair of 22-yard punts in the second quarter.

Ryan was cut by the Packers earlier this month. He was expected to open the season as Green Bay’s punter, but the Packers signed Derrick Frost, who had been released by Washington.

That was just one of Seattle’s roster moves this week. McMullen will be the next. McMullen was originally drafted by Philadelphia in 2003, played with the Eagles until 2005 and played for the Vikings last season. He did not play in the NFL last year and was waived by Washington before the regular-season began. He arrived in Seattle on Monday for a tryout as part of a group of wide receivers. He agreed to a one-year contract. Samie Parker, formerly of Kansas City, was also a player Seattle considered.

Kent is a split end, the same position as Nate Burleson who was placed on injured reserve because of a torn knee ligament. He played in the Buffalo game but did not catch a pass, and when Holmgren was asked if Kent would step into the starting role after Burleson’s injury, the coach said that wasn’t necessarily the case.

Kent was released Tuesday along with Forsett, a rookie who was inactive in Sunday’s game. Both Kent and Forsett are eligible for the practice squad, and the Seahawks have one spot to fill on that unit. Either could also return to the active roster.

Michael Bumpus — a practice-squad member — is also a candidate for the 53-man roster. The Seahawks are carrying two kickers and could release rookie Brandon Coutu.

Danny O’Neil: 206-464-2364 or doneil@seattletimes.com