SAN DIEGO -- Two weeks ago, with Fernando Tatis Jr. nursing a potentially season-ending back injury, the Padres asked Luis Urías to step in and fill the void at shortstop.

Those shoes aren't easy to fill. Before he went down, Tatis had quickly established himself as one of the most dazzling young defenders in the game. Urias, meanwhile, had played some shortstop in the Minor Leagues. But he's undoubtedly a second baseman.

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Urias hasn’t made many mistakes since the position switch. But he picked a bad time for a big one on Wednesday night.

With two outs in the 10th inning, Dodgers catcher Russell Martin hit a sharp one-hopper to Urias’ right. The rookie infielder made an impressive backhand stop and spun to set his feet. But his throw sailed high, and Enrique Hernandez scampered home with the go-ahead run in Los Angeles’ 6-4 victory at Petco Park.

“I think everything happened too fast,” Urias said afterward. “Obviously, I didn't want to throw it like that. It happened. I can learn from it.”

If anything, it seemed as though Urias had too much time after he fielded Martin’s 104 mph rocket.

“It's a very nice catch,” said Padres manager Andy Green. “He just got a little casual there. ... It's a young guy playing shortstop. He made a great stab. He just didn't complete the throw.”

It was a disheartening finish after San Diego had rallied from a late two-run deficit. Eric Hosmer’s solo homer in the eighth cut it to one, before Francisco Mejía scored on Kenley Jansen’s wild pitch in the ninth, tying the game. The Dodgers responded immediately.

“You want to win the game,” Hosmer said. “You're not looking for the little things. At the end of the day, you've got to seal the deal.”

Adding insult to injury, the extra-innings defeat clocked in at four hours and five minutes. Following a 6:10 p.m. PT start time, that left the Padres unable to take off for San Francisco ahead of the curfew at San Diego International Airport. They’re now slated to fly Thursday morning, with their series opener against the Giants on Thursday night.

A week ago, the Padres returned home, set to welcome Major League Baseball’s two reigning pennant winners for a six-game homestand at Petco Park. What better measuring stick for an organization than half a dozen games against World Series-caliber opposition?

The results made one thing clear: The Padres have a gap to close before they can begin to consider themselves contenders. San Diego dropped two of three against Boston over the weekend, then two more against the Dodgers this week. The Padres haven’t won a season series against their rivals to the north since 2010.

“We went [2-4] on the homestand,” Hosmer said. “That's definitely not up to our expectation.”

For most of the night, San Diego's planned bullpen game went smoothly. The Dodgers plated three in the second against Trey Wingenter, a career reliever who was making his first professional start. But the seven relievers who followed combined to allow one earned run over 8 2/3.

Still, the Padres fell to 0-5 on bullpen days this season. (That doesn’t count games in which they’ve used an opener or games in which their starter exited earlier than expected). This bullpen game figures to have a lingering impact, too. The Padres are in the midst of a stretch with 13 games in 13 days, and they used eight relievers Wednesday.

In the 10th, Green called for Kirby Yates. A lights-out closer, Yates has struggled in non-save situations this season. But Green didn’t have much of a choice. His only other option was the newly recalled Nick Margevicius.

For the most part, Yates was sharp. He recorded two quick outs before Enrique Hernandez walked and stole second. Hernandez said he noticed Mejia favoring his side after sliding into second base the inning prior.

“Warming up, he was lobbing it to the pitcher, then he lobbed it to second base, and I was like, ‘If he can’t throw, I’m going to go,’” Hernandez said. “I found a way to get to first, told [first-base coach George Lombard], ‘If he gives me a high leg kick, I’m going to go.’ Sure enough, he got his leg up, and I took off.”

It would’ve been for naught, except Urias’ throw to first base sailed high. There are still some questions as to why Urias is at shortstop. When Tatis went down earlier in the season, Manny Machado slid to short, and Ty France filled in at third base. Now, France and Greg Garcia are part of a timeshare at second.

That’s mostly because the Padres want to find out what France brings to the table at second -- because he’s unlikely to see much playing time in the future with Machado entrenched at third. But it’s partly because the club has confidence in Urias at short, too.

“He's done some really nice things out there,” Green said of Urias. “He's still young at shortstop in the big leagues. He's an incredibly young kid who's played a lot of second base throughout his entire career. There will be some mistakes from time to time. We've liked a lot of what he's done.”