Martin had opened the ninth by drawing a walk on five pitches.
"[Umpire Jeff Nelson] had a good strike zone," said Hoffman. "Those balls were missing. There's obviously a fine line, but those leadoff walks will hurt you."
Indeed, Martin, whose RBI double had tied the game in the seventh, moved to second on a bunt by Blake DeWitt and scored on Hu's looped single.
"He got inside of the pitch enough to keep it fair," said Hoffman. "It's a game of inches again, and I wasn't able to get the changeup down in the zone where he was going to swing over it."
Jonathan Broxton (1-0), who pitched out of a first-and-third, one-out situation in the eighth, got the win, and Hoffman (0-2) took the loss. Takashi Saito came on in the ninth to pick up his first save of the season, retiring the Padres in order.
Both starters pitched solid games.
Chris Young tossed seven innings for the Padres, allowing two runs on five hits. He walked three and struck out eight.
Derek Lowe pitched six innings for the Dodgers, allowing two runs, one earned, on five hits. He walked one and struck out six.
Andre Ethier was Young's main nemesis, hitting a home run into the beach area to lead off the second inning and then singling, stealing second and scoring on Martin's double in the seventh.
"I didn't locate that [home run] pitch very well," said Young. "And then [Ethier] had a tough at-bat there in the seventh. I thought I had him struck out, but he tipped a ball that went into the catcher's mitt and fell out, and then he was able to find a hole with the ground ball, but that's the way it goes."
Both teams' shortstops, Khalil Greene and Rafael Furcal, saved runs with leaping one-handed grabs, Greene in the third for the Padres, and Furcal in the eighth for the Dodgers.
The Padres had taken a 2-1 lead in the bottom of the sixth, taking advantage of some shoddy fielding by the Dodgers, who had flashed a lot of leather earlier in the game.
Tadahito Iguchi reached safely on an error by Furcal, whose throw to first base bounced and handcuffed first baseman James Loney.
Adrian Gonzalez followed with a single to center, sending Iguchi to third. Iguchi scored on a sacrifice fly to right by Kevin Kouzmanoff.
The Dodgers had taken a 1-0 lead on Ethier's homer, which equaled the total number of home runs Young gave up in 13 starts in PETCO Park last season.
The Padres tied the game at 1 in the bottom of the third on an RBI double by Gonzalez that scored Iguchi all the way from first.
Heath Bell, like Broxton, pitched his way out of a first-and-third, one-out jam in the eighth, striking out Andruw Jones and getting Ethier on a flyout to left.
"I got Jones in a situation where everyone was throwing him sliders or curveballs away, and that's the way I was thinking, but I changed my mind and went fastball away, and I think I just froze him," said Bell. "I was hoping to a get a little 'W' right there, but oh well."
"The [Dodgers] wriggled out of some jams, starting in the first inning," said manger Bud Black. "Lowe did a good job, and so did Broxton and Bell for us."
The Padres had runners at second and third in the first but didn't score. Then, in the third, Brian Giles led off with a double, and Iguchi hit a sharp grounder headed for center field. Second baseman Hu made a diving stop, losing his glove, and though he couldn't make a play at first, he saw Giles run past third base and threw him out trying to get back.
"That's the way it goes. You're not going to win every game," said Giles. "We just didn't get the big hits."
The Padres, who finished their first homestand at 4-3, head to San Francisco for a three-game series before traveling to Los Angeles for another series with the Dodgers next weekend.