"We're very excited to add Ryan to our organization," Rutherford said. "He will be a regular in our top-12, and he will add both size and a physical presence."
The 6-foot-1, 225-pound Reaves is signed through the 2017-18 season, and he carries a salary of $1.125 million.
Pittsburgh gives up the 31st overall pick in the first round this year, while gaining the 51st overall selection in the second round from St. Louis. Sundqvist had spent a majority of the past two seasons with the Penguins' AHL affiliate in Wilkes-Barre/Scranton.
Reaves, 30, is coming off of his best NHL season, setting career highs in goals (7), assists (6) and points (13), in addition to collecting 104 penalty minutes in 80 games played with the Blues. He also skated in 11 postseason contests with St. Louis.
Reaves led the Blues, and finished 10th in the NHL, with 239 hits this past season. That marked the fourth-straight year that the Winnipeg, Manitoba native has surpassed the 200-hit plateau.
Reaves was originally chosen by the Blues in the fifth round (156th overall) in the 2005 NHL Draft. He has skated in 419 career NHL regular-season contests with St. Louis, netting 27 goals, 24 assists and 51 points with 695 penalty minutes. Reaves has added one goal in 36 playoff contests.
Before turning pro, Reaves skated for three seasons with the Brandon Wheat Kings in the Western Hockey League.
