"He's kind of the effectively wild guy," Mattingly said.
Almost sounds dangerous.
League was acquired from Seattle last July and decided to stay in Los Angeles, agreeing in October to a $22.5 million, three-year contract.
Originally slotted as a middle reliever, he took over as closer when Kenley Jansen was sidelined between Aug. 27 and Sept. 20 due to an irregular heartbeat.
League was 6 for 6 in save chances with the Dodgers, going 2-1 with a 2.30 ERA in 48 games after the trade. He walked 14 in 27 1-3 innings for Los Angeles and 33 in 72 innings.
"It can be an uncomfortable bat for anybody," Mattingly said. "For me, he's always been a guy with tremendous stuff. His stuff has been all over the place, and has always been on the verge of being wild. You don't know if he's going to throw a strike or not. When he's not throwing strikes, he gets in worse counts, and he's going to get hit a little more."
Pitching coach Rick Honeycutt and Ken Howell -- then the bullpen coach and now assistant pitching coach -- worked to restore the location of League's sinker and its power.
"Kenny and Rick made a simple adjustment," Mattingly said. "But I think part of the adjustment was a change of scenery for the guy."
League became a first-time All-Star in 2011, when he had a 2.63 ERA and 10 walks in 61 1-3 innings. But he was dropped as closer in late May last year after a succession of erratic outings.
"You get to come somewhere that's a fresh look," Mattingly said. "Somebody suggests in a drill, `This is what we're seeing, try this.' It clicks. It's like, he's back."
League says he feels closer to home in Los Angeles. He plans to live this season in Manhattan Beach, which reminds him of growing up in Hawaii. In the offseason, he lives with his wife Sasha and his three children in San Diego.
"I'll leave my surfboards at home," League said.
NOTES: Dodgers INF Justin Sellers said Thursday his motorcycle arrest in Sacramento last month on misdemeanor charges of reckless driving and evading arrest was "a misunderstanding." Sellers denied driving recklessly and said he didn't pull over because he thought a police officer was pulling a prank on him. ... Mattingly got his first look Thursday at South Korean LHP Hyun-Jin Ryu, who threw about 40 pitches in his first bullpen session. "He's pretty smooth," said Mattingly, who had only seen video of Ryu. A.J. Ellis caught for Ryu. Ellis worked with Ryu a few times in South Korea. "You've got be encouraged by what you see," Ellis said.