SAN DIEGO -- It was only a couple of days ago that Brewers manager Ron Roenicke called Mark Kotsay the finest pinch-hitter he had ever seen. Ever -- as in all 36 of Roenicke's years as a professional player, coach and manager.On Tuesday night, Kotsay showed his former manager what the Brewers are missing. He delivered a pinch-hit, two-run home run in the eighth inning that accounted for the only offense in a 2-0 Padres' win at Petco Park. Kotsay's blow off Brewers reliever Francisco Rodriguez was particularly stinging, on a couple of fronts. It spoiled Shaun Marcum's scoreless, seven-inning start and perpetuated Rodriguez's recent troubles. Then there's the fact the Brewers would rather Kotsay be wearing their uniform for a second season. Instead, he signed with the Padres in November, mere weeks after making the Brewers' final out of 2011. Kotsay previously played here and has had a home in San Diego since 2003. "I certainly would have loved to have him back, but I understand when you play a long time and have a chance to be home," Roenicke said. "He's a good player. He's one of those rare guys who can hit with the game on the line against those top relievers." Rodriguez qualifies as such, but he is in the sort of rough patch Brewers fans never saw during the second half of 2011, after Rodriguez came over from the Mets and, with fellow setup men LaTroy Hawkins and Takashi Saito, and closer John Axford, gave the Brewers lights-out relief in the late innings. Including Will Venable's single and Kotsay's game-breaking home run on Tuesday, Rodriguez has allowed 12 hits and eight walks in 12 1/3 innings so far. Those baserunners have led to an 0-3 record, nine earned runs and a 6.57 ERA. "It's been frustrating," Rodriguez said. "I have not been consistent at all, the whole year long, five weeks already into the season. I'm healthy. My arm feels fine. If anything, it's location. I have to be able to stop making mistakes and start putting zeroes on the board. I know what I'm capable of doing. I know I can do a way better job than I have been." The decisive fastball to Kotsay, Rodriguez said, "was right down the middle. Right in his wheelhouse. He's a veteran. He's a guy who knows how to hit. He's been doing that for so many years. A guy like that, you cannot make a mistake when the game is on the line." Roenicke, who has known Rodriguez for a decade, back to K-Rod's coming out party with the 2002 World Series champion Angels, is keeping the faith. He approached Rodriguez in the clubhouse to offer support. "It's command; his stuff is fine," Roenicke said. "He'll make some great pitches and then when he makes a mistake, they're hitting the ball right now. He's a guy that we need out there. Every time we bring him in, I feel like he's going to do the job. He's certainly still a great reliever, and he'll be fine." The series is even at a game apiece with Wednesday's rubber match to go. A night after Ryan Braun turned this spacious park into his personal playground with the Brewers and Padres combining for 11 runs, the pitchers ruled on Tuesday. Marcum and Edinson Volquez worked seven scoreless innings on three hits apiece, Marcum leading in both strikeouts (six), walks (four) and escapes. The Padres put a runner on base against Marcum in five different innings and had a man in scoring position in four of them. Marcum escaped each time. "Really good. Really mixed his speeds well," Roenicke said. "This should be a ballgame to really get him locked in." Marcum has penned quality starts in four of his five outings. "In this ballpark, too, you can kind of pitch to the ballpark, pitch away, away, away," he said. "The main thing was keeping the ball down so they couldn't get the ball elevated in the gaps." The Brewers had fewer opportunities against Volquez, who walked two and struck out four. Their best chance came in the second inning, when Travis Ishikawa walked with one out and Alex Gonzalez singled. Milwaukee catcher Jonathan Lucroy grounded into a double play to start an 0-for-3 night. The teams remained locked in a scoreless tie into the eighth inning, when Rodriguez surrendered a one-out single to Venable that bounced up the middle. Kotsay followed as a pinch-hitter and connected with a fastball in a 1-and-1 count, narrowly clearing the right-field fence. It was the Padres' first pinch-hit home run this season and Kotsay's first since August 2002, during his first tour of duty with the Padres. "It was a wall-scraper, I had my doubts off the bat," Kotsay said. Huston Street retired the Brewers in order in the ninth inning for his fourth save.