There's always demand for quality left handers at the trade deadline, but this year, they're in short supply. Bruce Chen, Will Ohman and Javier Lopez could probably be acquired and Alan Embree and Scott Schoeneweis could be signed as free agents. There are not many left-handers to choose from, and that only increases Scott Downs' trade value.
The Blue Jays, below .500 after a June-long slump, would presumably listen on Downs, who hits free agency after the season. The 34-year-old lefty has an affordable $4MM salary and some impressive stats. In 35.1 innings, he has a 2.80 ERA with 7.1 K/9 and 1.8 BB/9. He is allowing less than one hit per inning pitched and boasts a characteristically high 55% ground ball rate. He's arguably the best left-handed reliever available this summer.
The Blue Jays have no reason to settle for anything less than a highly-touted prospect. Not only is Downs pitching well, he now ranks as a Type A free agent in the latest Elias rankings. That means the Jays can obtain two high picks in next year's draft if Downs turns down an offer of arbitration to sign elsewhere. We can't assume that the Blue Jays are willing to offer Downs arbitration, but they have just $39MM committed to next year's payroll, so paying Downs $5MM or so in 2011 appears possible under the team's budget.
Essentially, the Blue Jays can't lose as long as Downs stays healthy and continues pitching well enough to maintain his Type A status. Either someone offers a compelling package and the Blue Jays get talent now, or they keep Downs and offer arbitration. If he accepts the offer, the Jays have a quality reliever on a one-year deal. If he declines and signs elsewhere, they have two top picks in next year's draft.