What top prospect Puk’s arrival means for A’s

At last, we may see the Athletics’ No. 2 prospect pitch in a major league game.

The A’s are expected to call up left-hander A.J. Puk on Tuesday in time for a crucial series against the Yankees. Here are some questions answered about the call-up.

What role will Puk play in the bullpen?

Puk but could turn out to be the jet-fuel that may ignite a stagnant and struggling bullpen as this postseason push progresses.

The 24-year-old left-hander has a 98 mph fastball and 90 mph slider with a curveball. The most important attribute: he misses bats, a key piece in every successful bullpen this era that the A’s have generally been lacking. The Athletics’ bullpen K/9 rate is a bottom-dwelling 8.82 and ranks 19th in MLB in strikeout percentage at 23%. The Yankees, Astros and Rays, comparatively, rank third, fourth and fifth with around a 25% rate.

The Jake Diekman deadline acquisition certainly helped fill a blatant southpaw void the A’s glossed over with just Ryan Buchter and Wei-Chung Wang dishing from the left until then. Diekman has found his groove after giving up a couple runs (two) and walks (three) in his first three appearances, he’s given up just one earned run over his last seven outings with just three strikeouts.

Wang was optioned Monday afternoon, apparently to make room for Puk on the active roster. He hadn’t been a go-to option of late; he’d last pitched two innings in a lopsided loss to the Chicago Cubs.

Puk certainly has the velocity and repertoire to not only complement Diekman’s stability with a bit more fire, but elevate the A’s late-inning punch left murky that had been disappointing seasons from Lou Trivino and Blake Treinen.

Wait, isn’t Puk a starter?

Puk is certainly one of the premier starters of the A’s future rotation that could boast Jesus Luzardo, Frankie Montas and James Kaprielian, too.

But his Tommy John recovery dictates that Puk pitch a limited number of innings at this point, just 18 months removed from the surgery itself. Puk has yet to even pitch back-to-back days in the minor leagues this season, but has the stuff worthy of a big-league promotion.

How did Puk do in the minor leagues?

Puk pitched 25? innings for the Las Vegas Aviators, Midland Rockhounds and Stockton Ports this year. In that time, he recorded a 4.97 ERA with 38 strikeouts and 10 walks.

Those numbers are a little scary, but inflated given the state of his recovery at times of collapse. His last outing with Las Vegas yielded two strikeouts in one inning of work. The consistency of his stuff - the velocity, in particular - should play at the big-league level.

Will he get to pitch soon?

The A’s are good about getting those opportunities for call-ups ASAP, and he could throw a wrench into the Yankees’ reign of home run terror.

Oakland’s bullpen was overworked in a long four-game series that included an extra-inning win against the Houston Astros, and should benefit from Monday’s off day. But Puk’s call-up could provide even more cushion. And Puk could be the man this series in particular.

The Yankees feed off contact - any ball hit in the air has a good chance of landing over the fence - and most of the A’s pitching staff relies on soft contact.

Puk’s propensity for the strikeout could neuter a late-inning power surge. Gary Sanchez has just five of his 27 home runs off lefties, and his OPS is 50 points lower against lefties over righties. Brett Gardner’s OPS is .626 against lefties and .879 against righties. On the other side, though, Aaron Judge’s OPS is a whopping 1.067 against lefties, .759 against righties.

Numbers aside, Puk could be an X-factor in this series, and a key cog in a fluid bullpen as September baseball looms. Plus, his fellow top prospect Jesus Luzardo may not be too far behind.