From Tarik El-Bashir of the Washington Post:
Left wing Matt Cooke, as expected, will not be returning to Washington. The signing of Matt Bradley made Cooke expendable/redundant. "Obviously, Matt Bradley has been with us longer and was committed to us," McPhee said. "You can't keep everybody."
Read more from Capitals Insider here.
Cooke was a solid addition to the Caps' roster at the trade deadline but the qualities he brings to the table--energy, physical play and speed have been deemed replaceable by the Caps management. I'm sure Cooke will catch on in a third/fourth line role with another squad.