SAN DIEGO — Carson Seymour had a decision to make in the sixth inning Tuesday night.

The San Francisco Giants right-hander fielded a comebacker with one out and runners at the corners. If he had paused to check the San Diego Padres runner at third base, he would have seen that Elias Díaz, a catcher with 5th-percentile sprint speed, had committed to running home. But Seymour did not opt for the waddling bird in the hand. Instead, he whirled toward second base and made a wide throw. He was fortunate that infielder Christian Koss not only kept the ball from skipping into center field but also kept a toe on the bag.

The Giants only recorded one out. Díaz scored to give the Padres a 5-1 lead. Should Seymour have thrown to the plate?

“(It’s) probably the safest play at that point in time,” Giants manager Bob Melvin said. “If he does make a good throw to second base, we might get the double play. So, you know, with the score of the game, maybe the easiest thing is to take the out at home.”

When you play the Padres this season, any run they tack on is a lethal dose. Nick Pivetta threw high fastballs past the Giants for six innings and the Giants received no relief or reward to get him out of the game. Adrian Morejon, Jason Adam and Robert Suarez each tossed a scoreless inning, allowing one baserunner between them, while protecting the Padres’ 5-1 victory and continuing what’s been a suffocating run for San Diego relievers against their NL West opponent.

Jung Hoo Lee supplied the only Giants run of the game — a leadoff home run in the first inning. (Denis Poroy / Imagn Images)

The Giants haven’t scored a run against San Diego’s bullpen since June 4. The Padres’ scoreless streak against the Giants is at 26 1/3 relief innings. And only two of those innings have been thrown by new acquisition Mason Miller, the All-Star former A’s closer whose 103 mph fastball drew audible gasps from the crowd when it registered on the scoreboard last week in San Francisco.

“They’ve got good stuff and they throw a lot of strikes,” Giants catcher Patrick Bailey said. “It’s one of the hardest throwing bullpens in the league. They all got good heaters that are definitely verty, throwing in the upper 90s to 100, and they’ve all got pretty good offspeed pitches that they trust as well. They’ve got one of the best ‘pens in the league and we’ve just got to do a better job one through nine sticking to our game plan.”

When Bailey compliments Padres relievers on their “verty” fastballs, he is speaking about induced vertical break — essentially, the amount of ride or late life that a pitcher creates independent of gravity. The Padres bullpen averages 17.7 inches of induced vertical break on fastballs, which is the most in the major leagues. The Los Angeles Dodgers are next with 17.1 inches.

The Giants are sixth at 16.3 inches, but only one current reliever in their group, closer Randy Rodriguez, has a fastball that exceeds that average. Another, Hayden Birdsong, pitched in relief earlier this season before transitioning to the rotation — and then back to Triple-A Sacramento when his command and confidence abandoned him.

A bullpen does not need to be super verty to be effective. The Giants’ core four relievers, vital to winning three World Series championships from 2010-14, were mostly spin doctors who succeeded by winning platoon matchups and preventing barreled contact. Then again, the three-batter minimum wasn’t on the books back then.

These days, the most certain way to shut the door is to slam it closed. And the Padres, after adding at the trade deadline, have their assortment of door slammers all locked up for the foreseeable future. Suarez is the only one of their core relievers who can become a free agent after this season, assuming he opts out of the two years and $16 million remaining on his contract.

The Giants have far, far less certainty. They subtracted from their bullpen at the trade deadline, trading closer Camilo Doval and right-hander Tyler Rogers. Rogers is coming up on free agency and there’s always a chance he re-signs with the Giants this winter. But for now, the Giants don’t have relievers (other than Rodriguez and Ryan Walker) who they could consider locks to open the season in next year’s bullpen.

They also received more discouraging news about left-hander Erik Miller, who paused his rehab assignment because of recurring left elbow inflammation. Miller won’t pick up a baseball for two weeks and it’s looking less likely that he will ramp back up in time to pitch this season.

“It got back to the point where we have to be careful,” Melvin said of Miller.

The Giants have had to exercise caution all year with Rodriguez, too, after the right-hander missed five weeks with elbow inflammation last season. Rodriguez was unscored upon in 40 of his first 43 appearances and was a deserving addition to the NL All-Star team, but it’s been a little spotty since he was elevated to replace Doval in the closer role. He’s allowed runs in three of seven appearances and his fastball velocity has been down a touch. With the Giants constantly trailing on the past two homestands, Rodriguez went nine days in between appearances.

Rodriguez’s success is due in part to his judicious usage. He’s made back-to-back appearances just six times this season and he hasn’t appeared on three consecutive days. At some point, though, the Giants will have to find out how well Rodriguez can bounce back when pushed a little harder, as closers need to be from time to time — especially in the postseason.

“Walker’s closed really well too,” Melvin said. “Every year is not going to look the same. Randy is still kind of transitioning to the closer role as well. But they’re both really talented guys who should be pitching at the back end of the bullpen.”

How the Giants go about constructing the rest of that bullpen is an open question. There will be high-profile choices in free agency other than (possibly) Suarez and Rogers; Mets closer Edwin Díaz can opt out of his contract and Aroldis Chapman will be on the open market. But from Armando Benitez to Mark Melancon to smaller bets like Luke Jackson that turned messy, the Giants’ recent investments in free-agent relievers would’ve turned out better if they’d put the money in a meme stock. This hasn’t been the kind of problem that they have solved by throwing money at it.

Perhaps Birdsong finds a permanent home for his “verty” fastball in the bullpen. Perhaps Jose Buttó can elevate his profile from the back-end role he filled with the Mets. Perhaps Keaton Winn can stay healthy and have success as a two-pitch guy in a relief role. Perhaps right-hander Trent Harris, a 26-year-old who was hurtling toward the big leagues before hitting a rough patch at Triple-A Sacramento, will reemerge as the next Ryan Walker type. Perhaps some of the lower-level arms in the system can advance quickly, but don’t count on it.

For all the rise in the prospect rankings the Giants have made this season, there isn’t a lot of pitching in the pipeline. Eight of their nine top prospects are position players, according to MLB.com, and the lone pitcher, Carson Whisenhunt, was way too hittable in his first foray against big-league hitters.

Giants president Buster Posey will try to find a way to solve the team’s lineup problem against fastballs and surround their core with scrappy hitters who put the ball in play. He’ll have to determine how much of next year’s rotation can be filled in-house. They still want to blueprint winning with pitching and defense, especially at their waterfront ballpark, where they’ve had the antithesis of a home-field advantage since the All-Star break.

But even if they accomplish all of those goals in a satisfactory way, they still need to slam the door. And compared to some of their NL West adversaries, they have a lot of work to do.

(Top photo of Ramon Laureano and Patrick Bailey: Denis Poroy / Imagn Images)