If only the starter had as much good fortune against the rest of the 51s' slugger-laden lineup.
The D-backs' top prospect struck out seven over six up-an-down innings in a 6-5, 10-inning loss that snapped the Reno Aces' five-game winning streak.
Despite giving up three runs on a season-high nine hits, Bauer left encouraged.
"I thought it was my second-best outing all year, ironically enough," he said. "Maybe I need to throw bad next time.
"I had command of everything. The ball was coming out of my hand well, I had command of my off-speed pitches, I felt good."
Making his fourth Triple-A start, Bauer got off to an inauspicious beginning. He required 29 pitches to get out of the first, a frame in which Travis d'Arnaud's two-out single scored Adeiny Hechavarria.
It didn't get easier from there. Aside from a 1-2-3, five-pitch fifth, Bauer allowed the 51s to advance a runner to second base in every inning.
An otherwise strong performance came apart in the sixth before his pitch count peaked at 100. Singles by Eric Thames and Moises Sierra and a walk to Anthony Gose loaded the bases and all but Gose -- who was thrown out at the plate -- came around to score on Hechavarria's two-out double.
"They only hit two balls hard all night," Bauer said. "Nothing they really squared up, except for the doubles, and they really squared up those."
All told, Bauer threw 67 pitches in the strike zone while issuing a pair of free passes.
The night marked a conclusion of a challenging two-start stretch in the Pacific Coast League. Before he outdueled Guerrero, Bauer bested Sacramento home run threats Manny Ramirez and Yoenis Cespedes for his second Triple-A win on Monday.
"He was just another hitter in the box," Bauer said of Guerrero, who finished 1-for-5, "but I wasn't going to pitch away from him, I wasn't going to walk him."
Through four Triple-A outings, the former UCLA standout -- and the third overall pick in last year's Draft -- is 2-0 with a 2.52 ERA and 31 strikeouts over 25 innings.
"I think I've been doing pretty well," Bauer said. "My numbers maybe don't look quite as well, but they're not hitting me very hard. I feel good."
Despite the un-Bauer-like pitching line, he was still in line for victory No. 3. But Sierra, who homered three times in Friday's series finale with Tucson, helped change that. The Blue Jays' No. 19 prospect slugged a two-run homer in the eighth off reliever Jensen Lewis as the 51s tied it at 5-5. Sierra went 4-for-4.
Las Vegas walked off with the win in the 10th against reliever Taylor Sinclair (0-1) as d'Arnaud walked, took third on Yan Gomes' single and trotted home two batters later on Jonathan Diaz's bases-loaded base on balls.
Aaron Laffey pitched seven innings for the 51s, yielding four runs -- two earned -- on nine hits. He didn't factor in the decision.
Aces leadoff man and D-backs' No. 15 prospect Adam Eaton went 3-for-5 with a first-inning solo shot off Laffey.