"It's something that's obviously unacceptable at any time," Sveum said. "Whether we could have turned the double play is irrelevant to not knowing how many outs there are in the most important part of the game.
"These things have to stop happening or we're just going to stop playing [him]," Sveum said. "These kind of things are things my son does in high school -- maybe."
Did Sveum consider benching Castro at that point?
"No," Sveum said. "I can't take him out. I'll have a good talking to him. It's the last straw. If he wants to play, he better start getting his head in the game, period."
It was Castro's second "brain fart" -- as Sveum calls them -- in the series. On Friday, the shortstop also tried to steal at the wrong time and didn't slide.
"It's very embarrassing," Castro said. "I apologized to my team and everybody. That kind of thing is not supposed to happen."
The shortstop had been playing much better defense in recent weeks.
"I've been playing defense pretty well, but that kind of thing, you have to pay attention more," Castro said. "Those kind of things can't happen. It's very embarrassing for me and my teammates and the manager and everybody. I apologized to all of them."
Samardzija put his arm around Castro in the dugout and shared some of the blame.
"What I take away from it as a pitcher is I can't let the bases get loaded with no outs," Samardzija said. "I walk a guy, give up a hit, fell behind in the count, leave the ball over the plate, and before you know it, the bases are loaded and we're forcing the defense to make plays."
Sveum wondered out loud before the game whether his team had set a record by not being able to score meaningful runs in an inning in their last nine losses. In 15 losses since May 16, the Cubs have scored 15 earned runs over 102 innings against starting pitchers, who have a combined 1.32 ERA.
The Cubs tried to rectify that in the second against Ryan Vogelsong (4-2) when Steve Clevenger and Samardzija both delivered RBI singles with two outs. But the first three Giants batters in the second rapped hits off Samardzija, capped by Crawford's RBI double to close to 2-1.
After San Francisco tied it in the fifth, Carlos Marmol (0-2) took over in the seventh and walked Buster Posey and was then hit on the right hip by a line drive by Angel Pagan. Brandon Belt walked to load the bases and Marmol got Arias to hit into a double play, but the go-ahead run scored.
"If [Marmol] could just stay away from the walks -- I don't care who you are, they're going to bite you in the butt before it's all said and done," Sveum said.
Samardzija exited after giving up two runs on seven hits and five walks over five innings.
"He had the 'just misses,'" Sveum said of the right-hander. "It wasn't like all over the place, it was just misses that got him into a high pitch count and got him into a little trouble. It wasn't horrible. There were a lot of good at-bats and foul balls early. He just couldn't get it to that outer part of the plate. He battled."
"I need to be in the zone early in the count -- it's kind of a broken record when I have outings like this," Samardzija said. "We need to get that first-pitch strike and then we need that first leadoff hitter of the inning out, and I didn't do that today and I put myself in a hole every inning and was forcing myself to make pitches, tough pitches that were making me work too much."
"We had to scratch and claw for runs," Giants manager Bruce Bochy said. "Really, the games could have gone either way. But the pitching came through for us. ... A hit here or there changes the game."
With the loss, the Cubs now have dropped 11 straight games on the road for the first time since June 18-29, 1954.
"[The attitude] has been fine," Sveum said. "I don't have any concerns about the attitude before the games and the preparation. The attitude, like I said, that's not the problem. The problem is winning baseball games and scoring runs is the problem."