Larry Stone suggests that the Mariners could wait to trade Erik Bedard or Jarrod Washburn after the July 31 deadline:

I wanted to throw out another possibility that hasn't been mentioned much: The Mariners could hedge their bets at the trade deadline, with regards to their two big-ticket items, Erik Bedard and Jarrod Washburn.

As most of you know, the term "trade deadline" is a misnomer. Trades can be and are made after July 31. They can be made year-round, in fact. The only catch is that after July 31, through the end of the season, anyone who is traded must clear waivers. The next deadline to worry about is actually Aug. 31 -- players must be on a team's roster by that date to be eligible for the post-season.

I suppose it's possible the Mariners could wait, but bold actions might be required here. Bedard is making $7.75 million this year; Washburn is making $10.35 million. By August, though, they'll each only have a couple million dollars apiece left on their contracts, so they probably won't clear waivers, and the Mariners will have limited options if they want to deal them. Bedard and Washburn's value would likely decline, too, as the rental period on them would dwindle to one month instead of two. 

The Mariners are currently behind both the Angels and the Rangers in the AL West. Of course we don't yet know what Bedard and Washburn would fetch on the market, but I think it's likely that Seattle's best bet would be to honestly weigh the chances that Bedard and Washburn can carry them through the postseason (very slim, in my opinion, although they've made enormous strides since last year) and try to trade them before the July 31 deadline. It probably wouldn't be a very popular with the fans, but the Mariners have a very flawed team right now, and with Jack Zduriencik in charge and a large payroll, they could have a juggernaut in a few years.