Sounders FC’s dramatic offseason turnover continued Friday with another head-turning move.

The team acquired the rights to veteran forward Kenny Cooper, who scored 18 goals in 2012, and an undisclosed amount of allocation money from FC Dallas in exchange for midfielder Adam Moffat.

Cooper still has to come to terms with Seattle after having made $342,500 last season. Dallas had declined a contract option on the 29-year-old for 2014.

The Sounders’ wild week has also seen the acquisition of Chad Marshall, a two-time MLS defender of the year, and Stefan Frei, who could be the team’s starting goalkeeper.

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“Kenny is a proven goal-scorer who is extremely active in the box,” said coach Sigi Schmid in a news release. “At 6 foot 3, he is a big forward who creates matchup problems for opposing defenders.”

Seattle would be the fourth team in four years for Cooper, whose 72 MLS goals are seventh-most among active players. He has made 10 appearances for the U.S. national team, scoring four goals.

The potential addition comes with an added implication, notably that Eddie Johnson looks increasingly likely to be on his way out. The Washington Post reported Friday that three MLS teams and a European team are interested in the polarizing Sounders forward.

Moffat had been acquired by Seattle in a September trade for midfielder Servando Carrasco. The 27-year-old joins a significant list of departures this week, joining goalkeeper Michael Gspurning, defender Marc Burch and midfielders Steve Zakuani and Mauro Rosales.

• Sounders FC’s road game against Chivas USA on June 11 has been moved to Sept. 3. Kickoff will be at 7:30 p.m.

Joshua Mayers: 206-464-3184 or jmayers@seattletimes.com.

On Twitter @joshuamayers