Snell improved his record to 2-1 as he tossed seven scoreless innings.
"[Snell] has the makings of what you would definitely describe on a staff as a big-time stopper," Pirates manager Jim Tracy said. "That's what it's beginning to look like. This guy has come so far in a short period of time. He's to be given an awful lot of credit for that -- not only as a baseball player but also as a person, too. This guy is becoming something very special."
Snell had confidence in all of his pitches.
"That's been a good theme this year for me," said Snell, who gave up six hits Friday. "I worked hard in the offseason to locate my pitches better and make my pitches more crisp when I needed them. ... Another thing that I'm learning to do -- take speed off and not try to throw hard all the time."
Reds players praised Snell, whose 1.59 ERA is among the lowest in the Majors.
"I think he's done this to us a few times," Reds first baseman Scott Hatteberg said. "He doesn't have a pitch that's just overwhelming. He just throws a lot of different pitches for strikes. He knows how to pitch."
Reds starter Eric Milton lasted just 4 1/3 innings and was tagged for three runs and six hits. It was Milton's shortest outing of the season as the embattled left-hander fell to 0-4.
The Pirates jumped on Milton in the bottom of the first inning. Hot-hitting Jason Bay delivered a two-run double to left-center field. Bay came into the contest on a tear, batting .361 (13-for-36) with three doubles, one triple, one homer, eight RBIs and four runs in his last nine games. The hot streak had lifted Bay's batting average from .167 to .282. Pittsburgh tacked on another run as Adam LaRoche came through with an RBI single, giving the Pirates a 3-0 lead.
Milton lasted to the bottom of the fifth inning when the Pirates mounted another threat. Jack Wilson led off with a double. Milton struck out Freddy Sanchez and then was replaced by right-hander Kirk Saarloos, who struck out Bay and retired Brad Eldred to end the inning.
Pirates closer Salomon Torres surrendered a ninth-inning home run to Adam Dunn, the slugger's fifth of the season. Torres has been scored upon in six of his last eight appearances, but he hung on to record his seventh save.
"Salomon made an adjustment tonight," Tracy said. "The one thing he did ... there was a lot of strikes thrown. OK, fine, the guy hit a solo home run to start the inning. But that's the starting point to get [Torres] back to where he was at at the beginning of the year. He went after [hitters], and we've got a good building block right there to move forward. I liked what he did."
Torres was pleased to get the save.
"It was like I told you guys earlier, I'm coming with my best stuff," Torres said. "Hit it if you can, and if you hit it out, I tip my cap. It wasn't time for me to be fooling around and being too passive. It wasn't pretty, but I would take 40 more of those."
George Von Benko is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.