Selected by the New York Rangers in the sixth round (No. 168) of the 2007 NHL Draft, Hagelin has 225 points (89 goals, 136 assists) in 504 regular-season games and 47 points (22 goals, 25 assists) in 121 Stanley Cup Playoff games.
Pearson, a 26-year-old forward, has one assist in 17 games this season. He had 40 points (15 goals, 25 assists) in 82 games last season.
"Our team is obviously not in a position that we are comfortable with in terms of how we are playing," Kings general manager Rob Blake said. "This is a change to our lineup that gives us an additional amount of speed. With Carl Hagelin, his No. 1 asset is speed and getting to holes, and we think he will play a big role on the penalty kill for us going forward."
Penguins coach Mike Sullivan said he expects Pearson to be available when Pittsburgh hosts the Tampa Bay Lightning on Thursday (7 p.m. ET; ATTSN-PT, SUN, TVAS, NHL.TV).
"He's a very good player," Sullivan said. "I think he's a guy that could help us offensively. I think he has the ability to play with some of our top people. He certainly did that when he was in [Los Angeles]. He's had a 20-goal season. He's had a 40-plus-point season or two. So he has shown an ability to produce offensively."
Selected by Los Angeles in the first round (No. 30) of the 2012 NHL Draft, Pearson has 144 points (69 goals, 75 assists) in 325 regular-season games with the Kings and 15 points (five goals, 10 assists) in 34 playoff games. He won the Stanley Cup with the Kings in 2014.
Pearson is signed through 2020-21 at an average annual value of $3.75 million; Hagelin signed a four-year contract with the Ducks on Aug. 14, 2015 and can become an unrestricted free agent July 1.
The Penguins (7-6-3), who lost 4-2 at the New Jersey Devils on Tuesday, are 1-5-1 in their past seven games and are seventh in the Metropolitan Division.
"I just think we're in a funk now," Rutherford said. "We're a fragile team. We're struggling. But for the most part, I still believe in this team."
Penguins forward Patric Hornqvist said Rutherford got his point across with the trade.
"This is part of the business. If you don't play well there are going to be changes," Hornqvist said. "That's exactly what happened. For me, personally, it's too bad it was that guy. ... Obviously, he sent a big message to the group. We have to be better."
The Kings (5-11-1) have lost three straight games, including 5-1 at home to the Toronto Maple Leafs on Tuesday. They have the fewest points in the NHL (11), have scored the fewest goals (34), and are 1-3-0 since firing coach John Stevens and replacing him with Willie Desjardins on Nov. 4. Los Angeles plays at the Chicago Blackhawks on Friday (8:30 p.m. ET; NHLN, NBCSCH, FS-W, NHL.TV).
