June 1st is a significant date in the NFL calendar for two reasons.
First, of course, is the salary cap accounting rule known as the "Post June 1st designation." Per that rule, introduced in 2006, teams are allowed to release two players early in the offseason (thus giving those players the chance to re-sign with a new team before the free agency bonanza is done) while designating him as a post-June 1st cut. This allows the releasing team to pro-rate bonus/dead money over two league year seasons, giving them a little short-term cap relief (instead of having to include all remaining bonus money in the current year). Some teams use this to manage cap room going forward, while others choose to simply eat the full charge of dead money.
For example, seven players were "post June 1st designations" in 2014 - Steelers OLB LaMarr Woodley, Cardinals OG Daryn Colledge, Giants C David Baas, Falcons' S Thomas DeCoud, Niners CB Carlos Rogers, Panthers WR Steve Smith, and Cowboys WR Miles Austin. The Seahawks released both Red Bryant and Chris Clemons without this designation, thus accelerating all of their dead money charges into 2014.
The second reason that June 1st is an important date on the NFL calendar is that it marks the first day of the offseason in which signing free agents does not affect the compensatory pick formula.
As Alex Marvez points out, "the NFL formula used to determine the extra selections annually granted for free-agent losses also takes into account the number of free agents a team signs before a June 1 deadline. To secure compensatory choices and potentially improve the round in which they are granted, some franchises are intentionally waiting until after June 1 to bolster their squads with veteran acquisitions."
While Seattle's depth remains strong at most positions, many had thought that they would hit free agency much harder than they did after losing key starters or role players in Clemons, Bryant, Brandon Browner, Walter Thurmond, Golden Tate, and Clinton McDonald, among others. Instead, the Seahawks focused on re-signing and retaining their own, extending Earl Thomas, Richard Sherman, and Doug Baldwin, then re-upping Tony McDaniel, Sidney Rice, and O'Brien Schofield among others.
That said, it will be interesting to see if the Seahawks do pursue some veteran free agents now that the compensatory pick formula is set - and the Seahawks will surely receive multiple comp picks next year for the losses they sustained. John Schneider, though, has noted numerous times during this offseason that the team had to turn away talented and experienced players in free agency this offseason -- guys that wanted to come and play for this team and these coaches -- in order to make sure the franchise saved money to extend and re-sign their key guys in Thomas, Sherman, and Baldwin. Now, Schneider has said that the team is not yet done in extending their own guys, but several of the top remaning free agents still on the market have shown interest in Seattle.
Free agent tight end Jermichael Finley visited Seattle earlier in the offseason and was recently cleared by his doctor for football activities. DT Kevin Williams made a visit to the VMAC as well, and cornerback Terrell Thomas has a history with Pete Carroll at USC. Other players still out there include WR Santonio Holmes, DT Ryan Pickett, OC Jonathan Goodwin, OT David Stewart, DE Brett Keisal, and DE Daniel Te'o-Nesheim.