Thirteen months after being honored as MLS Defender of the Year, Bobby Boswell is leaving D.C. United. Boswell, who lost and regained his starting spot several times last season and sat out the conference semifinal, first leg against Chicago (a 1-0 loss) that eventually eliminated D.C., 3-2, on aggregate, is the newest member of the two-time defending champion Houston Dynamo.

United accepted backup goalkeeper Zach Wells and a conditional 2009 draft pick in exchange for Boswell, 24, who was left unprotected in the expansion draft and during MLS Cup week indicated he'd probably be moving on.

The acquisition of Wells, 26, comes amid reports D.C. keeper Troy Perkins is being bought by Norwegian club Valerenga. Wells (6-foot-2, 187), played just four league matches for Houston in 2007; in 23 league appearances, he has a 1.17 goals-allowed average and 9-5-8 record. He also played four games in the CONCACAF Champions Cup and SuperLiga competitions.

Some observers regard him as one of the few backups in the league ready to step into a starting job, though D.C. is looking for another experienced keeper. The D.C. backup, Jay Nolly, played just one match last season.

Houston lost central defender Ryan Cochrane to San Jose in the expansion draft and can pair Boswell (6-foot-2, 185) with rugged veteran Eddie Robinson in the middle, though Patrick Ianni played well in spot duty last season and will be given a chance at a starting spot.

The Quakes also picked defenders Jason Hernandez (Chivas USA) and Clarence Goodson (FC Dallas), and the versatile James Riley, who played in the midfield and the back line for New England.

Coach Frank Yallop is preparing an offer for former Quake defender Ramiro Corrales, according to a source with extensive contacts in Scandanavia. Corrales plays for SK Brann in Norway, where solid starters can earn more than $200,000 per year.

Yallop has three major allocations available and could use some of that money to entice Corrales, 30, who was raised in the central California city of Salinas and is of Mexican heritage. He played for Yallop from 2001 to 2003; Yallop left after that season to coach Canada, and Corrales moved to Europe a year later.