SAN DIEGO — Try to wrap your heads around this one: The team with the best record in the Majors also has the most blown saves. 

One part of that sentence allows the Giants to sleep easier on nights like this. They are still, even after a 7-6 balk-off loss to the Padres that clinched a series loss here in San Diego, the best team in baseball record-wise. The other part of that sentence keeps the staff up at nights.

The Giants continually walk a tight rope in the late innings, and Santiago Casilla stumbled off of it Saturday, balking home the winning run and giving the Giants 18 blown saves in 92 games. 

Casilla’s night would have stood out regardless. He gave up three singles and two runs in the 10th. But it was magnified by what Sergio Romo did an inning earlier. The former closer struck out two in a perfect inning, throwing an unfair slider to Wil Myers and freezing Matt Kemp with a clever two-seamer. 

Afterward, Bochy tried to quiet any talk of switching roles. He said the Giants had this night set up just the way they wanted.

“One guy threw well, the other guy struggled,” Bochy said. “I don’t want to get in a situation where you’re flip-flopping guys. If you have to tweak it, you do. But Santiago, it’s been a while since he’s had a hiccup. He’s had a lot of rest (the last week), maybe too much, to where he wasn’t sharp.”

Casilla had locked up nine straight save opportunities and he had given up a run in just once of his previous 11 appearances. But this one was off the rails from the start. 

Casilla fell behind Alex Dickerson 2-0 and then gave up a single. Derek Norris lined a 2-1 fastball for another single. Casilla lost track of Norris, and he alertly stole second. 

“You get behind that first batter, that’s always tough,” catcher Buster Posey said. “The ball that Noris hit was a little more on the plate.”

Adam Rosales fell behind 0-2 but Casilla threw two straight in the dirt before Rosales poked a single past a drawn-in infield. With Alexei Ramirez up, Casilla came toward the plate and stumbled, his cleat sticking in the dirt. He tried to throw the ball anyway but the damage was done.

“It looked a little discombobulated on that balk,” Bochy said. “He’s going home and gets caught. He did the right thing and threw the ball. But he stutter-stepped and that was it, a balk.”

Casilla said his mechanics were fine on the pitch. His foot simply caught.

“It’s always frustrating,” he said through interpreter Erwin Higueros. “What’s more frustrating is I felt really good.”

What was more frustrating for the Giants was that they spent hours trying to fight back from a rough start. Jeff Samardzija gave up two homers and five runs in the first three innings, but he settled in near the end of his start and the bullpen let the lineup catch up. Angel Pagan hit a big homer and Mac Williamson and Ramiro Pena went deep in the sixth to tie it. 

Posey hit a high shot to right in the top of the 10th, his first career extra-innings homer. The Giants looked headed for a thrilling win, but it wasn’t to be. They have lost two in a row to a team they beat nine straight times in the first half. 

“Yesterday we seemed a little sluggish, but I thought today everything seemed normal,” Posey said. 

--- The Giants got good news on Hunter Pence. He came out of his rehab game after just three innings and was holding his right hamstring, but he might actually play on Sunday as planned. Bochy said Pence told trainers that the problem actually occurred when he was hit by a pitch in his first plate appearance, not on his single in the third. 

“He was trying to get out of the way and he thinks he aggravated,” the hamstring, Bochy said. “It got a little sore. We were being cautious.”

The Giants will reevaluate Pence on Sunday and he might be cleared to play. Originally, he was scheduled to play five innings Sunday and then take Monday off.