Brandon Morrow scored 5:15 into the third period, Jagr added a goal four minutes later, and Roussel iced the victory in the last two minutes.
"I thought we bent a little bit in that second period," Eakin said, "but we stuck with it and stuck with our system."
And in the process, they drew even with the Kings in the standings.
"They definitely have a different look from last year," Kings captain Dustin Brown said. "They have a lot of new guys in the lineup with a lot of energy. It's a divisional game, and they found a way to win."
NOTES: The Kings were on a serious roll coming, winning seven of their previous eight while outscoring opponents 30-16. Their 7-1-1 home record was tied for the fourth-best home start in club history. ... Kings center Jeff Carter, who is surging with 16 goals and 18 points in his past 20 games, ranks second in the NHL with 15 goals. Carter also leads the league in game-winning goals with four. ... Fellow center Anze Kopitar has 20 points in his past 18 games and 15 over the past 12. ... Dallas has won four of its past five games against the Kings, including the past three at Staples Center. ... Since returning from injury March 4, Stars center Derek Roy has 12 points, five of which have come in his past three games. Roy has nine points in seven games against the Kings. ... The Stars and Kings will play four more times against each other this season.