"I've never seen a grip like this with the results you see this pitch do," Scioscia said.
To off-set his fastball and curveball, Coello features an 80-mph pitch that dances and doesn't spin, like a knuckleball, but is thrown with a traditional forkball grip, wedged deep between his giant index and middle fingers.
Hitters can't seem to figure it out, observers have a hard time describing it.
"This thing comes out with virtually no spin on it," Scioscia said. "It really is closer to a knuckleball than it is a forkball."
Six years ago, Coello spent his first pro season with the Angels, but as a catcher. While growing up in Central Florida, he never pitched -- not in Little League, high school or junior college -- but the Angels liked his arm and felt his best career path came from a mound, even before knowing anything about this hybrid pitch he now throws.
"He wasn't bad behind the plate," said bullpen catcher Tom Gregorio, who was then in his first year as roving catching coordinator. "He had good hands, moved OK, just didn't swing the bat that great. We just felt he was gifted with a great arm. We felt that was his best opportunity to get to the big leagues."
Coello -- already 22 at the time -- ultimately relented to the position change, using his live arm to post a 1.37 ERA in 20 rookie-ball appearances. After the season, though, the Angels didn't re-sign him -- and neither did anybody else.
"They didn't know me," Coello said. "Nobody. Some friends of mine would call and be like, 'Hey, how's the catching going? What? You're pitching?'"
So Coello went to independent ball, where he rediscovered the gimmick pitch he used to toy around with while warming up. He introduced it in a game, gained confidence in it, mastered it and kept it in his back pocket to play up his fastball and curveball.
After pitching well in independent ball in 2009, Jamie Bane, son of former Angels scouting director Eddie Bane, signed him to the Red Sox's organization, where he spent the next two seasons before joining the Cubs in 2011 and spending last year with the Blue Jays.
"I didn't know how to throw a knuckleball," said Coello, who has posted a 3.40 ERA with a 1.24 WHIP and 10.1 strikeouts per nine innings in his Minor League career. "I'd try to throw the knuckleball and it wouldn't come out. My fingers would hurt. I'm opposite from everybody else."
Angels general manager Jerry Dipoto obtained Coello on a Minor League deal in late January, and since coming up to the Majors on May 12, he's been somewhat of a revelation, giving up one earned run in 12 1/3 innings while striking out 18 and walking two.
"Robert is kind of a late bloomer," Scioscia said, "and right now, he's throwing the ball better than he has in his life."
Coello will tell you everything still works off his fastball, which he throws in the low-90s. But that forkball-knuckleball pitch is what sets him apart, even if he only throws it on occasion.
"When it's really dancing and moving a lot, it's really difficult to catch," said catcher Chris Iannetta, who switches to the knuckleball mitt owned by bullpen coach Steve Soliz every time Coello checks in.
Asked for others who threw a similar pitch, both in movement and in grip, pitching coach Mike Butcher mentioned the forkballs of Jose Contreras and Bryan Harvey. Scioscia referenced the slower knuckleball of Tom Candiotti.
Gregorio had another comparison.
"I caught R.A. Dickey in Triple-A with Texas, and I kind of compare it to that," Gregorio said. "R.A. Dickey varies speed on his [knuckleball], and when he throws it hard, that's what I compare it to."