MIAMI — Runs have been hard to come by lately for the San Francisco Giants. The good news is their pitching staff has made it just as difficult for opponents to score.

San Francisco ended May with a major league-best 2.64 ERA while going 14 straight games without scoring more than four runs.

That theme continued in their series against the Miami Marlins, where they took two of three in South Florida. The Giants (33-26) reached the four-run threshold just once, in Sunday’s 4-2 win, while limiting the Marlins to just three runs over the three-game series.

“Any time you win a series on the road you have to feel good about it,” San Francisco manager Bob Melvin said, “especially the way we’ve been scoring runs. We’ll take it. It’d be nice offensively to break out some and put a little distance in some of these games.”

Matos Delivers 3-Run Blast on Sunday

In Sunday’s win, Wilmer Flores drove in a run with a groundout in the third. Luis Matos hit a three-run shot in the fourth. And that’s all the scoring San Francisco managed despite eight hits.

Matos’ homer, his fourth of the season, made it 4-0 and gave the Giants enough of a cushion to fend off Miami’s late threat.

“The way we’ve been scoring runs it felt like a 20-run homer at the time,” Melvin said. “We had to grind at the end. It’d be nice to not have to play that game every day, but (it was) a huge swing for a guy that works really hard every day … number gets called on a day like this where we’re not scoring any runs and has the biggest swing of the game.”

Their pitching in the series was excellent as it was the entire month of May, despite missing three-time Cy Young Award winner Justin Verlander, who remains out with a strained right pectoral muscle.

Harrison Sharp in Friday’s Win

They shut out Miami in the opener thanks to five sharp innings from Kyle Harrison, who made just his made his second start since moving to the rotation because of Verlander’s injury. The Giants limited the Marlins to three hits for a second straight game on Saturday despite losing 1-0.

Hayden Birdsong, another reliever-turned-starter, limited the Marlins to two hits through five innings on Sunday before giving up three in the sixth. San Francisco’s bullpen preserved the close win, with five relievers only giving up a run the rest of the way.

Their 2.64 ERA was the Giants best in a single month since posting a 1.91 ERA in September and October of 2010.

Despite their pitching, the Giants have scored just 30 runs over their last 14 games. The last time San Francisco scored four runs or fewer in 14 straight games in the same season was in 1976, when the Giants went 15 games without scoring that many.

“The runs will come. We’re hitting the ball . We’ve just got to find that one swing obviously late in the game to pull away, Birdsong said. “But we’re playing good baseball and if we keep it tight early we’ll play pretty well.”