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"This certainly solidifies our group of nine forwards," Armstrong told Jeremy Rutherford of the St. Louis Post-Dispatch. "We still have some areas that we need to fill in, but this (trade) wasn't done to set up for something else."
"T.J.'s a heck of a hockey player and was a very good player here, but I really think with his size and his style of play, we had players that played like that same style," Armstrong said. "Brouwer gives us a little bit of a different look."
At 6-foot-3 and 213 pounds, Brouwer notched 21 goals and added 22 assists while appearing in all 82 regular-season games for the Capitals. Oshie, who is 5-foot-11 and 189 pounds, scored 19 goals and added 36 assists in 72 regular-season contests.
Oshie registered two points in six playoff games in 2014-15, and he managed only nine points in 30 career postseason contests with the Blues.
"They'll all bring a different element to the game. If (head coach) Ken (Hitchcock) wants to use David back in the middle, playing him with Brouwer and whoever on the left side, it makes that a big, heavy line."
The Blues remain in negotiations with Tarasenko, but have yet to agree on a new deal with the restricted free agent.
The Oshie trade saves St. Louis about $500,000 next season and potentially about $4 million more in two years. Brouwer's cap hit is $3.66 million and he is a pending UFA in 2016-17, while Oshie counts against the cap for another two years at $4.175 million annually.
Armstrong said while the trade with the Capitals wasn't the precursor to another deal, that doesn't mean more changes won't be made.
"I never say never."