Giants rookie Shaun Anderson was pitching on an extra day of rest and had thrown just 72 pitches Friday night.
But after letting Anderson hit for himself in the top of the sixth inning, manager Bruce Bochy decided to pull his starter in the bottom half of the inning following a leadoff single by Daniel Murphy.
Considering that Anderson was pitching well and hadn't thrown a lot of pitches, it was a puzzling decision.
Bochy called on 28-year-old lefty Sam Selman to face Ryan McMahon, but that didn't go well.
McMahon greeted the rookie with a 422-foot homer to center field, erasing the Giants' two-run lead. In 47 minor league innings this season, Selman had allowed just one homer. In two innings with the Giants, he's now given up two homers.
After the game, Bochy was asked why he handled the sixth inning the way he did.
"I was going to try to get one more [inning] out of Anderson," Bochy told reporters in Colorado. "He had a couple good innings there, but once [he gave up] the base hit there, they had their lefties. Wanted to cover the kid. That area, to be honest, has been touch and go with him. I thought about it, but was trying to get through the sixth without going to the 'pen."
Reyes Moronta took over for Selman in the seventh and allowed a go-ahead double to Ian Desmond. The Rockies would go on to win 5-4 on Friday night.
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As for Anderson, after Friday's outing, he's at 114 2/3 innings pitched this season between Triple-A Sacramento and San Francisco. Last season, he topped out at a career-high 141 1/3 innings between Double-A Richmond and Sacramento.
While Anderson probably could have pitched one or two more innings Friday night given his pitch count, Bochy does have to keep an eye on the 24-year-old's workload. At some point in September, the Giants likely will shut Anderson down and tell him to get ready for 2020.