"I don't think he was quite 100 percent," said Padres manager Bud Black.
Not when it mattered most, as the Brewers scored five runs in the second inning and then hung on for their ninth consecutive victory, while the Padres keep drifting further and further back in the National League West.
At 5-15, the Padres have matched their worst start in franchise history after 20 games. The 1971 and '87 teams also began the season with five victories in their first 20 games.
"Things aren't going our way," Black said. "Our guys are playing hard. There's still 142 games left. We've dug ourselves a hole. There's no secrets. It will happen."
Even after Richard (0-2) allowed a run in the first, things looked rosy for the Padres in the bottom half, as they scored twice. Carlos Quentin, playing in his first game since his eight-game suspension ended, knocked in a run with a single off the third-base bag. The next batter, Yonder Alonso, knocked in a run with another single.
But the second inning proved to be Richard's undoing, as the Brewers sent 10 batters to the plate. The Brewers had five hits in the inning, three of which landed in right field off the left-handed Richard.
"It's one of those outings where I made a few good pitches and they put them in play," Richard said.
Rickie Weeks walked to start the inning and eventually scored on a two-run single by Yuniesky Betancourt. Jonathan Lucroy capped the rally with a two-run double to make it 6-2.
"The Brewers had good at-bats against him, taking the ball the other way. Good pieces of hitting. They strung some hits together," Black said.
Richard allowed six runs on six hits in 1 2/3 innings with two walks and one strikeout.
Richard's start marked the third time in his career that he pitched two innings or fewer. The last was on April 8, 2011, when he pitched one inning against the Dodgers, though the game was delayed because of rain. The other time was July 9, 2009, when he was with the White Sox.
Richard said there was no residual effect from the illness that caused him to miss a start against the Giants.
"It's just one of those things you deal with going through a season," Richard said. "It's a non-issue."
One of the few bright spots for the Padres on Tuesday was the pitching of reliever Thad Weber. Recalled from Triple-A Tucson on Saturday, Weber allowed two hits over 4 1/3 innings. Like he did on April 13 -- when he tossed 3 2/3 innings after a short start by Edinson Volquez -- Weber saved the bullpen.
"Obviously, I'd rather not see the early part of the game," Weber said. "That's my job, come up, eat innings. I was happy I was able to do my job. I threw a lot of good breaking balls tonight."
The Padres, down 6-2 early, got a run back in the bottom of the second on an RBI single by Will Venable.
In the fourth inning, the first two batters -- Jedd Gyorko and Nick Hundley -- reached, but the inning ended with Brewers' shortstop Jean Segura leaping to catch a liner off the bat of Everth Cabrera.
"The ball that Cabrera hit -- we got lucky," said Brewers manager Ron Roenicke. "Siggy made a nice play on it, but we got lucky. Huge double play."
In the seventh inning, the Padres loaded the bases on three consecutive two-out walks by Brewers starter Yovani Gallardo (2-1). But lefty reliever Tom Gorzelanny came in to strike out the left-handed-hitting Alonso to end the inning.