Shattenkirk, a highly coveted offensive minded defenseman was to hit the free agent market this coming off season, so the Blues made the deal before Wednesday's NHL trade deadline, assuring they would get something for the second leading scorer on the Blues this season.
Shattenkirk came to the Blues in a 2011 trade with the Colorado Avalanche. He scored 59 goals and added 199 assists in 425 career games with the Blues.
In a separate deal with the Capitals, the Blues acquired forward Brad Malone for minor league goalie Pheonix Copley. Oddly enough, Copley was acquired from the Capitals in 2015 in the trade involving T.J. Oshie.