CHICAGO -- Just when the Giants should be surging, they're still slumping. 
The offense's futility reached a new extreme with Sunday's 3-2, 13-inning loss to the Cubs. Their 17th loss in their last 24 road games concluded a series in which they mustered three hits in each of the first two games and four hits in the final two games.
This marked the first time that the Giants have collected four hits or fewer in four consecutive games since June 13-16, 1963. Their 14 hits against Chicago represented their lowest total for a four-game series since they had 13 in a set against the Dodgers on Aug. 14-17, 1992.
Buster Posey was in an 0-for-16 skid before he grounded an 11th-inning single. Brandon Belt is batting .204 since the All-Star break. Brandon Crawford is batting .163 (7-for-43) with runners in scoring position in the season's second half. Denard Span went 1-for-17 in the series.
"I think it's fair to say that we need to get some guys going with the bats," Giants manager Bruce Bochy said. "That's having a keen sense of the obvious, I guess. But that's what good pitching does. It shuts down hitting, and that's what [the Cubs] did."
A shutdown ninth inning would have given the Giants a series split. But Santiago Casilla yielded the second of Jason Heyward's three RBI singles, erasing San Francisco's 2-1 edge and forcing extra innings. Casilla absorbed his seventh blown save, the most by a Giants closer since Brian Wilson had seven in 2009. But Wilson had 45 save opportunities; Casilla has 37 with 26 games left.
San Francisco has lost five games when entering the ninth inning with a lead, third-most in the Major Leagues. The Giants happen to trail first-place Los Angeles by three games in the National League West. They do, however, still hold a Wild Card spot.
Bochy defended Casilla by saying, "This was a tough one, no getting around it. But it's tough to get down on somebody who has been doing a good job. Sure, he's had some hiccups. But there are other closers right there with him as far as saves."
This actually was an excellent collaborative effort for the Giants' bullpen. Except for Casilla and Matt Reynolds, who surrendered the winning run in the 13th, seven Giants relievers combined to allow one hit. Capitalizing on his 13-man bullpen, Bochy changed pitchers every inning after starter Johnny Cueto went the first seven.
"He loves to play the matchups," said veteran left-hander Javier López, who appeared in the eighth. "The [expanded] September roster affords him the opportunity to really do it if he needs to."
Among the Giants' proficient relievers was Joe Nathan, who was traded from San Francisco to Minnesota after the 2003 season. Nathan, 41, pitched a perfect 12th inning, concluding his outing by striking out Most Valuable Player candidate Kris Bryant.
Nathan, who ranks eighth all-time with 377 saves, echoed Bochy's defense of Casilla, saying that the right-hander has "electric stuff" and that the "sky's the limit for him." Nathan, who has recovered from two Tommy John surgeries, also pointed out that a closer can learn more by performing without his best stuff than when everything's going well.
But the Giants are running out of time to furnish this classroom.