SAN FRANCISCO – The Giants’ second-half collapse is easier to quantify than it is to qualify.

They charged into the All-Star break with the best record in baseball, setting a three-month pace for a 102-win season. Since then, they are 25-41 – the worst record in the NL, losing at a rate that extrapolates to a 101-loss season.

Here is how it breaks down:

Their hitters averaged 4.71 runs prior to the break – fourth best in the NL. They have averaged 3.83 runs since the break – worst in the NL. That’s a difference of minus-0.88 runs per game.

Their pitchers averaged 3.90 runs allowed prior to the break – fifth best in the NL. They have averaged 4.08 runs allowed since the break – second best in the NL. That’s a difference of plus-0.18 runs allowed per game.

Go back and reread that last paragraph, and it’s true: the Giants have given up the second fewest runs among NL teams since the break. Only the Chicago Cubs pitching staff has allowed fewer runs. And yet the Giants’ 25-41 record is the worst in the NL since the break.

One more exercise: Add up 0.88 fewer runs scored per game and 0.18 more runs allowed per game. You get 1.06.

That is the difference between a 102-win juggernaut and a 101-loss cesspool: 1.06 runs per game. And if that doesn’t sound like a whole lot, well, it isn’t.

Over one of the worst 66-game stretches in Giants history, one that put them on a 101-loss pace and destroyed an NL West lead that once stood at eight games, Bruce Bochy’s team has been outscored by just 16 runs.

That is amazing. Consider that the Cardinals, clearly a deficient team in so many respects, have been outscored by 43 runs in the second half, yet are 35-33 over that span. Even the spiraling Arizona Diamondbacks, who have been outscored by an NL-worst 90 runs, have a better record than the Giants in the second half. They’re 27-39.

There is some regression, of course. The Giants went 20-10 in one-run games prior to the break. They are 8-17 in one-run games since then. And it’s a pretty big swing, in addition to an emotional gut punch, when you add up the nine games they’ve lost when leading after eight innings compared to their zero comeback wins in 61 games when they trailed entering the ninth.

Those bullpen failures turned so many two-out-of-three series victories into two-out-of-three series losses – and likely had a hangover effect, too. The Giants have won a grand total of three series out of 21 since the break.

Yet the Giants just had their best day in the wild card standings in weeks on Monday. They moved up by standing still, because the Mets and Cardinals both lost.

For all that has gone against them, the Giants enter their final, six-game homestand of the season in the second wild card position, a half-game behind the Mets and one game in front of the Cardinals.

Those are the numbers.

As for the qualitative explanation, we turn to executive vice president Brian Sabean. We talked the other day for a story about the toll this second half has taken on Manager Bruce Bochy.

It has taken a toll on Sabean, too. He is a baseball architect, accustomed to building a team under certain physical laws and assumptions, and this second half has not adhered to any of them. It’s been a zero gravity environment. And in many ways, it defies explanation.

Here’s a transcript of our conversation about the general state of the team:

Q: How do you begin to explain what happened?

A: For all of us, it’s been a learning experience. You think you’ve seen it all and been through it all and obviously, this second half is something we can’t individually or collectively explain. Expectations were high after the first half, and we just didn’t take it onto the field.

The maddening thing is with the group we have, which is a talented group, a pretty experienced group, that it hasn’t corrected itself. That’s the human side of baseball, and when you lose the edge or the confidence or the swagger, it’s pretty humbling.

Q: For Bruce Bochy, it even involved watching a game from a hospital bed with an irregular heartbeat. Can you speak to the physical demands of the job on him, and how that might have affected his ability to manage?

A: I won’t speak to his health. That’s a personal thing. But all of us have to find different ways to decompress and shed that skin and move on to the next day. I’ve been here since 1993 and I’ve never seen stress like this that has been so maddening on a day-to-day basis.

Whether it’s him or anybody else, you realize it’s beyond your control. When it’s gone as far sideways as it has, and we’re talking the entire ballclub, there’s only so much you can do. I think you realize it’s up to the players.

Q: Even for a manager of Bochy’s reputation, the bullpen has been a puzzle he has not solved. Can someone even with his level of experience learn something, or take away a more informed perspective, based on those issues?

A: That’s age-old. Any manager, and I’ve had the pleasure to work with three really good ones, would rather have a dedicated man in the seventh, one in the eighth and a bona fide closer. But a lot of years, it doesn’t work that way. You are dealing with inexperience. You’ve got guys who will tell you they haven’t performed the way they expected. You have to continue to try to find a method to get through it, and Lord knows, this manager and coaching staff has met a lot of challenges in the past. You can’t sit down individually or collectively and come up with an overall reason it went so sideways, including the bullpen, because the talent is there. But you have to earn people’s trust to pitch in a certain role.

Q: The bullpen, obviously, has blown a franchise-record 30 saves this season. But the Giants almost never put a game away with their bats. They have played 55 one-run games, which is more than a third of their season. To what extent could carrying over more of the first-half offense have mitigated some of the bullpen issues?

A: To your point, we’ve underperformed across the board and in almost every department. There isn’t one player in the lineup having a career year or performing beyond the norm.

Felipe Alou had a great saying: when you become a leaky boat, it only takes one leak on a given day to put you on the wrong side of the score. We’ve done it with not enough starting pitching, with the bullpen work, by not adding on. We haven’t played the clean baseball we’re used to. That’s based on defense, pitching and timely hitting.

Q: You also went one 30-game stretch in which you committed just one error as a team. That is incredible. And you have been in every game, with a chance to win every series – even when you lost three of four at Wrigley Field.

A: The one gratifying thing about the Cubs series is we went toe to toe with them in their place. I think everyone knows we could’ve won three of four. But again, you’re on the wrong end of the results. We had the look of turning corner (after sweeping at) Arizona, and laid an egg (at home) in the San Diego series. Sustaining the momentum just hasn’t been possible for whatever reason.

Q: With no knowledge of how it happened, you’d assume, just looking at the winning percentage from one half to the next, that you sustained major, crippling injuries like the shattered ankle that ended Buster Posey’s season in 2011. Instead, the reverse is true. You got players like Hunter Pence and Joe Panik back. Even Angel Pagan has stayed off the DL in the second half. You could put out a lineup with seven players who have made All-Star teams. So what went missing?

A: There’s no question to me the effort is there and no question we have talent, but it is tougher and tougher for us to win a major league game. In our league, it comes down to pitching and there’s going to be pitching you haven’t faced before, and you don’t have a road map to mount an attack. That’s the nature of the game in the NL. The only other caveat is that we’re not known for the home run, and it’s the inability to break open a game and take some of the pressure off, we don’t have that luxury to do that.

If you’re not going to hit (home runs), you can’t give them up. In the past, we haven’t given them up. And there was a point in the season when we were.

We nose dived so badly into being a second division team that you think at some point, you’ll come out of it, get back to playing .500 and make a move. But we haven’t been able to bail the boat out. You think you’re sailing along and all of the sudden it’s not so smooth.

There are a lot of clichés that apply: you’re never as good as you are when you’re playing your best. Did any of you guys think this club would have the best record in baseball in first half, and be (24 games over) .500? Of course not. But for it to take such a dramatic right turn, and not maintain some semblance of consistency, it wears on everybody.

And all of this we’re talking about isn’t on Boch. You’re talking about an experienced coaching staff that’s been through a lot.

Q: And yet, as of this moment, you would be a playoff team.

A: Well, the challenge is at hand. We’ve inflicted a lot of pain on other folks in the past and had it our way. Things have a way of coming around. Now having said that, there’s six games left, and texting back and forth with Boch and the staff, it’s as simple as this: a lot of this group has done it before, so you can’t count them out. And you know a lot of this group will die on the sword before they give up.

But to the bigger question: It’s human nature that you want to find a direct way to explain it, and there might not be one, other than it being a collective failure.