Who will bring the lumber for the San Francisco Giants?

The Giants have a trusted recipe for postseason success.

It starts with tremendous starting pitching. Then you add in equal parts bullpen and defense. Sprinkle in some timely hitting by unlikely heroes and voila ... you’re parading down Market Street.

It seems pretty simple, but it’s not. Not this year, at least. The Giants possess some of the ingredients, trotting out four quality starters, led by Madison Bumgarner and Johnny Cueto, and a defense that remains rock-solid, anchored by shortstop Brandon Crawford and catcher Buster Posey.

It’s the shaky bullpen and the weak hitting that gives one pause heading into the National League Division Series against the Cubs. The Giants survived the wild-card game by riding Bumgarner for nine innings. And Cueto was waiting in the bullpen to relieve him in the win-or-go-home game.

That’s not exactly a vote of confidence from manager Bruce Bochy. But there’s not much he can do about it at this point. Looks like Sergio Romo will start the playoffs as the closer. Everyone else’s role is in flux.

The bigger problem might be the timely hitting. Conor Gillaspie joined the long list of unlikely postseason heroes who have lifted the Giants to three recent titles. Conor, meet Edgar Renteria and Cody Ross and Marco Scutaro and Travis Ishikawa. My colleague Scott Ostler calls them the Giants’ Whozat Heroes, and that’s as good a name as any. (Somewhere, Brian Doyle and Bernie Carbo nod in agreement. ...)

But can the Giants beat the juggernaut Cubs with the occasional hit from the likes of Gillaspie? Unlikely. Kris Bryant, Anthony Rizzo & Co. will need to be counterpunched with the bats of Posey and Brandon Belt and Hunter Pence. The meat of the Giants’ order needs to show up for San Francisco to pull off the upset.

Though none of those three has had tremendous a postseason at the plate in the past — Posey and Belt are career .241 hitters in the fall, Pence comes in at .258 — there is big-hit precedent from these three. Think of Belt’s 18th-inning blast to beat the Nationals in 2014. Or Posey’s grand slam against the Reds in 2012. Pence batted .444 against the Royals in the 2014 World Series.

After a miserable second half in which all three batters struggled to produce, one could argue that they are due. Belt caught fire at the end of the season, and nearly poked a Noah Syndergaard laser over the head of Curtis Granderson in center field Wednesday night.

It says here that the Giants’ fortunes will ride on the bats of the big three, batting second, third and fourth in Bochy’s lineup.

We’d be remiss to leave Crawford, the No. 5 hitter, out of this conversation. Known for his slick fielding and flowing hair, the man Aubrey Huff dubbed “Stamos” just finished another solid season at the plate, hitting a career-high .275. He’ll give the Giants quality at-bats, alongside double-play partner, Joe Panik.

Those are the expected stars hefting the lumber. But we know it’s often the man you’d least expect who comes up with the big knock.

So, who’s left to give the Giants the unexpected bump they’ve come to expect? Gillaspie stands poised to continue a Cinderella return to San Francisco, thriving for a team that once let him go. Angel Pagan is still dangerous. Ehire Adrianza? Not so much.

That leaves Denard Span on my list of possible contributors. And, considering the Giants’ history, why not?

If Posey and Belt and Pence don’t come through, surely we can count on Span the Man.