Bailey (3-2) has been up and down to start the season, but he found his form over 7 1/3 innings against the Rockies in holding them to four hits, with the only run coming on Charlie Blackmon's leadoff shot in the fourth. Bailey was largely responsible for Arenado's streak of reaching base ending at 30 games, and he was also a big reason the Rockies could not afford poor execution.
"We probably could've given up two instead of four," Rockies manager Walt Weiss said. "He threw the ball well. It was going to be hard to get a big inning against him."
Bailey said: "Those guys can do some damage. I pitched in pretty well, but I made a mistake on one pitch and left the ball up."
The defeat gave the Rockies (23-17) their first series loss since they dropped two of three at San Francisco from April 11-13. It also dropped them to 2-3 on their current road stretch. The Rockies play at Kansas City on Tuesday and Wednesday before returning home Friday to meet the Padres and start a six-game, seven-day homestand.
Despite Sunday's loss, Weiss was encouraged by the Rockies' start, which had them playing 40 games in 42 days before Monday's off-day. After finishing 74-88 last season, the Rockies are playing near the top of the National League West despite injuries.
Starting pitchers Brett Anderson (broken left index finger) and Tyler Chatwood (strained right flexor tendon) are out until possibly July. Defending NL batting champ Michael Cuddyer (left hamstring strain) was injured April 17, but if running goes well on Tuesday and Wednesday in Kansas City, he could go to Scottsdale, Ariz., for a brief rehab and return quickly. Regular catcher Wilin Rosario and utility infielder Josh Rutledge are on the disabled list with the flu.
"We compete every day, and we had to right out of the gate with the way the schedule was set up and the injuries we've had to deal with," Weiss said.
All nine of Blackmon's homers have been from the leadoff spot, which has him tied with the Brewers' Carlos Gomez for most top-of-the-order homers this season.
"In the offseason, I worked on keeping my swing in the zone longer, more up the middle, a little more follow through, and it's just kind of showing up when guys leave pitches over the plate," said Blackmon, who hit a hanging slider.
The Rockies had a chance after Blackmon's homer. Corey Dickerson singled but was caught stealing with Troy Tulowitzki up, and the inning fizzled.
Bailey struck out six and walked two, with his most important work coming in the fifth with a 3-1 lead. Morneau walked and Michael McKenry doubled to begin the inning. But Bailey enticed DJ LeMahieu to swing through a high 0-2 pitch -- after LeMahieu had fouled off the previous two pitches.
"He had his 'A' game, and he had total command of his fastball," LeMahieu said. "I don't think we squared up his fastball all day. He pitched both sides of the plate and mixed up speeds. When you can throw 95 and locate, that's tough to hit."
Bailey also fanned Rockies starting pitcher Juan Nicasio (4-2), and he worked Blackmon into a soft pop in third-base foul territory.
"I had a chance with two guys in scoring position and with two strikes I had to protect," said Blackmon, who also flied out in foul territory in the eighth. "He ended up making a good pitch on me, and I ended up fouling out. This park has, like, the least amount of foul territory anywhere. I don't know how you foul out twice in one game, with runners on base, too. That's not very productive."
Colorado's lack of execution started early. Reds leadoff man Billy Hamilton bounced to the right side in the first, but Morneau's toss to first sailed errantly past LeMahieu, who was covering the bag. Hamilton raced to third and scored on Skip Schumaker's bouncer.
The Reds' Ramon Santiago led off the third with a single, advanced to second on Bailey's bunt and took third on a balk. With two down, Schumaker singled into center.
With one out in the fourth, the Reds' Todd Frazier hit his second homer of the series and seventh of the season.
Santiago doubled to open the fifth and was at third with two outs when Nicasio worked Brandon Phillips into a bouncer to third. Arenado hesitated before forcing Morneau to leap to catch the throw.
A defending Rawlings Gold Glove Award winner at third and the first rookie to win it at that position, Arenado has a bevy of highlight plays, but in 40 games this year he has seven errors -- four fewer than he had last season in 130 defensive games.
"Sometimes it could be arm slot, and third base you throw from a lower slot, and it might run on you a little bit," Weiss said. "But I know he's saved a bunch more than he's let in. He's saved many runs this year."
Reds left-hander Aroldis Chapman made his first appearance since being hit in the face with a line drive on March 19, and he entered to wild applause. His first four pitches, to Tulowitzki, were shown on the scoreboard at 100 mph. Tulowitzki drew a walk, but Chapman fanned Carlos Gonzalez, Arenado and Morneau, punctuating the save with a downward fist swipe.