Adam Kilgore of the Washington Post has the story:
Morse boasts a .297/.343/.515 batting line since the start of the 2011 season. He also has 49 home runs and 157 RBI in that span. But the 30-year-old isn’t a good defensive player and is currently slated to become a free agent in November. He’ll presumably serve as the Mariners’ starting left fielder and part-time designated hitter.
Jaso, 29, hit .276/.394/.456 with 10 home runs and 50 RBI in 108 games last year for Seattle.
Cole, 21, had a 4.04 ERA and 1.25 WHIP in 89 innings last season between two levels of Single-A.
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UPDATE, 7:14 PM: CBS Sports’ Danny Knobler says the Nats will will also get two additional prospects.
UPDATE, 7:48 PM: Blake Treinen is one of those prospects, according to the Nationals. The other will be a player to be named later. Treinen, a righty, had a 4.37 ERA in 103 innings last year at High-A Stockton.