Coleman had a 1.69 ERA with one save in three games for Omaha. He spent most of last season with the Royals, appearing in 48 games with a 2.87 ERA, a 1-4 record and one save. He also racked up 64 strikeouts in 59 2/3 innings.
Dyson had been called up in the wake of Lorenzo Cain's groin injury that put him on the 15-day disabled list on Thursday. Dyson played center field and led off in the Friday and Saturday games against the Indians, and was 2-for-8 with two runs scored, getting thrown out in his only steal attempt.
"We need pitching, that's just it," manager Ned Yost said. "We really saw improvement in Dyson the two days he was here, especially offensively. But the way we've gone the last couple of days, our starters going short and using up the bullpen, has put us short down there, so we brought up Louis Coleman for added protection."
The move gives the Royals 13 pitchers for the first time this season, with eight in the bullpen instead of seven. The 'pen was stretched thin in the first two games against the Indians, when starters Luke Hochevar and Jonathan Sanchez lasted just four and 2 2/3 innings, respectively.
Coleman has the capability of pitching long relief, important now that long man Everett Teaford might be needed to start on Wednesday night against the Tigers if Hochevar's sore ankle doesn't heal in time.
"We were just looking for an available arm and the last time he threw was on the 10th," Yost said. "He's up to 50 pitches so he gives us some depth. He's a real good guy, especially against right-handed hitters."
Dyson sat solemnly in a hooded sweatshirt in front of his locker after getting the news.
"They said they need pitching," Dyson said. "It's all right, it's just part of the game."
Dyson had difficulty tracking a fly ball in the wind and missed it in Friday's game, and had a drive fall out of his glove after a long run in Saturday's game. Both went for triples and both came in big innings for the Indians.
"It was tough circumstances," Yost said. "Both days the wind was howling out there and the ball got up in the jet stream, and he made a couple real nice close plays, too, on balls that no one else would've gotten near."
When called up, Dyson was hitting .364 for Omaha and was 6-for-6 in steal attempts.
"He was catalystic, that's all I heard," Yost said. "He was getting on the base and creating havoc. He was playing really well, hitting the ball good, creating rallies, right in the middle of the offense."
The decision to move Dyson was, in part, because he's a left-handed batter and veteran backup Mitch Maier, also a lefty, is out of Minor League options. The other reserve outfielder is Jason Bourgeois.
"Bourgeois has an option left, but he's the only right-handed bat off the bench," Yost said.
Maier was in center field in the Royals' lineup on Sunday.
Dyson's departure also prompted Alex Gordon's return to the leadoff spot and Jeff Francoeur dropping back into the fifth spot. Yuniesky Betancourt, who belted a game-tying home run in Saturday night's 10-inning, 11-9 loss to the Indians, is slowed by an ankle sprain, so Chris Getz was at second base on Sunday.
Gordon, Getz in the two-hole and Eric Hosmer batting third gave the lineup three left-handed batters at the top for the first time this season.
"Yuni has been battling a slight sprained ankle and Getz gives us protection there, so it was the only thing we could do," Yost said.
Alcides Escobar, a right-handed batter, was 2-for-14 in his three turns at batting second.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.