Walt Weiss was hired Nov. 8. He officially became the Rockies' manager Tuesday night.

As he walked to the mound to remove Jhoulys Chacin, Weiss was booed. Not lustily, or with vigor, but there was enough noise to provide a clear signal of the fans' agitation over sticking with Chacin through six batters in the seventh inning.

For the second consecutive start, Chacin made a huge lead disappear, undermined by a defensive error. Closer Rafael Betancourt exited with an injury, but Wilin Rosario eased the pain with a walk-off single in the Rockies' 5-4 victory in 10 innings.

"Everything that happened to that point is just baseball, but we figured out a way to win," Betancourt said.

Weiss' decision became a footnote when the offense camouflaged the strategy. Facing erstwhile Rockie Matt Reynolds, Rosario lined the first pitch he saw into right field, scoring Carlos Gonzalez, who had doubled with one out, from second base.

The Rockies have won four of their past six games and moved within one game of the first-place Diamondbacks in the National League West.

There's concern for Betancourt, who will undergo an MRI on Wednesday. He spun awkwardly on his second pitch in the 10th inning, leaving with a tight right groin. He's listed as day to day, but has had leg issues in the past that must be monitored closely.

"I've been dealing with it for about (three weeks)," Betancourt said. "I don't think it's serious, but we'll know more tomorrow. I use my legs a lot, and I just couldn't push off."

Weiss has earned high marks from players for granting them freedom, while remaining firmly in control. He understands how hard the game is, outfielder Michael Cuddyer explained. Weiss provides a green light on the bases, and more often than not, on 3-0 pitches. Troy Tulowitzki homered in that situation in the third inning Tuesday.

"He lets us play. And he never panics," Gonzalez said.