Ramon Castro backed Santana with a three-run homer, and resurgent Carlos Delgado had three more hits on a muggy night at Shea Stadium. Delgado is batting .429 (15-for-35) in nine games this month.
The Giants have lost four of five and were shut out for the second straight game for the first time since Oakland did it June 9-10 last year, according to the Elias Sports Bureau. They haven't scored since Ray Durham's ninth-inning sacrifice fly in Sunday's 5-3 loss to the Los Angeles Dodgers.
Santana (8-7) was 0-4 despite a terrific 2.48 ERA in his previous six starts, leading the two-time Cy Young Award winner to say he was doing his job after a close loss to the Yankees. It was only the sixth time in his career that he has lost three or more consecutive decisions - he has never dropped five in a row.
The left-hander allowed three hits, walked three and struck out five in his shortest outing since he pitched three innings in his last start for Minnesota, a 9-4 loss at Detroit on Sept. 26.
Santana, Aaron Heilman, Duaner Sanchez and Joe Smith combined to retire San Francisco's last 13 batters and finish the Mets' first consecutive shutouts since Sept. 6-7, 2006.
The Giants managed only three hits for the second straight night.
New York took the lead in the fourth against Jonathan Sanchez (8-5), who was 5-0 with a 3.00 ERA in his previous six road starts.
Delgado doubled with two outs and Fernando Tatis kept the inning alive with a walk. Castro then hit a 1-2 pitch to left for his third homer.
Santana got two quick outs in the fifth before it started raining heavily with Durham at the plate. The water-logged crowd of 48,896 groaned as Durham walked, but cheered when Randy Winn flied out to end the inning, making it an official game.
Sanchez was pulled when the game resumed after a 42-minute delay. The left-hander allowed three hits, walked three and struck out six.
Argenis Reyes and Jose Reyes each had a run-scoring single in the eighth for New York. It was Argenis Reyes' first major league RBI.
The Giants put runners on first and second with two outs in the third and fourth, but couldn't come up with the big hit. Winn flied out to end the third and Emmanuel Burriss grounded out for the final out of the fourth.
