Joe Giradi now has the weapon Joe Maddon rode last October all the way to the Cubs first World Series championship since 1908, a weapon the Yankees gave the Cubs.

Aroldis Chapman is back to being a beast closing games. Over his past seven games, Chapman has fired eight innings and allowed just three hits while striking out 13. He has not allowed a run over that span.

Credit pitching coach Larry Rothschild for coming up with the solution to Chapman’s problem and Chapman with making the adjustment that was desperately needed.

Baseball is a game of inches, sometimes even less than that.

Chapman’s fastball was cutting too much. The lefty could not command the pitch and was getting behind in the count, creating his own mess. Rothschild had to figure a way to get Chapman to fix his delivery without making a significant change.

So the veteran pitching coach had Chapman put some separation between his middle finger and his index finger, giving him a wider grip and also had Chapman overlap the seams — in essence making it a four-seam fastball grip.

In the past Chapman would have his two fingers together and to the side of seams.

This has made a world of difference and the Yankees, who begin a critical series in Toronto on Friday night, have their true closer back. Dellin Betances has struggled — that is Rothschild’s next project — but David Robertson has been spectacular, so Girardi has plenty of options at the end of a game.

Chapman, 29, is thrilled with the change, telling The Post through interpreter Marlon Abreu, “I’m getting better command on the pitch, it’s a little more straight.’’

Straight, in this case, is good because he is having great success elevating the pitch to change the eye level of the hitters and at that height and location, you just can’t catch up to 100-plus mph.

Command remains a pitcher’s best friend, make no mistake about that.

“I was more on top of the seam with my old grip,’’ Chapman said. “Now I am using the traditional four-seam grip.’’

Noted Rothschild, “He had to get behind the baseball and stay behind it.’’

This is the Chapman the Yankees paid $86 million over five years as a free agent — after they dealt him to the Cubs last July to become the final piece of Theo Epstein’s puzzle.

Maddon rode the free agent hard and was rewarded, breaking the Curse of the Billy Goat in Chicago. Chapman started to wear out by the end, but you can’t blame Maddon for getting the most out of him while he could, and now Chapman said he is ready for a back-to-back postseason battle.

The Yankees essentially have the first wild card wrapped up and are three games back of the Red Sox with 10 to play for the AL East title. It is going to be difficult to catch Boston. If they don’t, the Yankees will host the wild-card game Oct. 3 — win that game and they get to take on the Indians or Astros in the Division Series.

Chapman said he is ready for another heavy October workload.

“That’s the objective: to get to the playoffs. We are three games behind in the division, we want to see if we can win it,’’ Chapman said of the AL East race. “I definitely am ready [for a run]. I’m prepared for it mentally and physically. Hopefully we have the opportunity.’’

Chapman was humbled a bit by his issues before coming up with the grip fix. Before turning it around he went through a six-game stretch during which he suffered a 10.50 ERA.

He has a completely clean slate and hopes to make the most of it.

You can be sure Girardi will use Chapman at every turn. He had Chapman warming up in the ninth with a six-run lead a week ago, so Chapman better be ready with his new grip for this busy run.