Rangers designated hitter Joey Gallo is greeted in the dugout...

Rangers designated hitter Joey Gallo is greeted in the dugout after scoring during the fourth inning against the Tigers on July 22 in Detroit. Credit: AP/Carlos Osorio

The only number anyone really needs to know about the Wednesday night trade that’s in the process of sending Joey Gallo to the Bronx is 314.

Of course that’s the distance, in feet, from home plate to the rightfield foul pole at Yankee Stadium. And with a short porch not far beyond, Gallo’s powerful lefty bat is going to do some serious damage at his new home.

Not just the ballpark itself. We’re talking about the No. 4 train.

Why it took so long for Brian Cashman to fit a lefthanded slugger for pinstripes is a mystery. Throughout history, the Yankees have built their championship pedigree on a foundation of legendary lefties -- Ruth, Gehrig, Maris, Yogi, Reggie -- and some of a more recent dynasty vintage, like Paul O’Neill, Tino Martinez and Hideki Matsui.

But in assembling his (failed) title bids over the past few years, Cashman had developed a blind spot for that side of the plate. Rather than strive for balance, the GM explained his current batch of righty hitters were capable of producing regardless. Power is power, Cashman reasoned, and that theory came back to bite him this season.

The daily lament, as the Yankees tumbled further behind the Red Sox, was the fact they were too one-dimensional. The worst of it? The Yankees featured an ill-fitting lineup for their own stadium. Too often, visiting teams partied in the short porch more than the owners of the place.

Those days should now be over.

Gallo is hardly the perfect baseball player. He’s a career .211 hitter and king of the sport’s three true outcomes: Gallo has homered, struck out or walked in 58.3% of his career plate appearances.

But he also has a very specific talent that the Yankees severely lack: an ability to mash the ball from the left side. Gallo has 138 home runs since 2017, the most of any lefty hitter over the past five seasons (according to stat guru Katie Sharp). In other words, Cashman -- who prides himself on collecting "big, hairy monsters" -- needed to import this one from Texas in order to help salvage this season.

Just look at what the Yankees were surviving on before Gallo’s arrival. They ranked 24th overall in runs per game with 4.16 before Wednesday’s trade, were tied for eighth in the AL with 127 homers and their leader from the left side was Rougned Odor, who had 12 through 62 games. The only other "impact" lefties have been 37-year-old Brett Gardner (four HRs, .312 slugging) and recent callups like Estevan Florial and switch-hitter Greg Allen.

Since the All-Star break, and during Aaron Judge’s stay on the COVID IL, the Yankees had been forced to remake themselves to some degree, relying more on the speed of the promoted RailRiders to scrape up runs. But Cashman’s roster isn’t built to win that way, and Gallo will help them get back to the bash-bullying style that’s baked into this group’s DNA.

At this deadline, Cashman’s path to improving the Yankees was fairly straightforward. Despite this team’s head-scratching ability to fluctuate between contention and catastrophe, the rotation has been excellent lately and the bullpen -- at least on paper -- should be sufficient when pitching to its potential. Now that Aroldis Chapman looks fixed again, that’s a huge confidence-booster.

The problem was always squeezing more out of the listless offense, as too many players weren’t performing to Cashman’s championship vision for this roster. Giancarlo Stanton, in particular, has been a trainwreck at the plate, hacking away at sliders that he couldn’t reach with a flagpole. Heading into Wednesday’s game against the Rays, Stanton had one homer in his last 66 plate appearances, hitting .207 (12-for-58) with 24 strikeouts and a .310 slugging percentage over that 15-game span.

Gallo should help pick up that slack, with the assumption that the streaky Stanton will heat up eventually. And if there were any doubt, Cashman’s trade for Gallo made it clear the Yankees’ goal for 2021 hasn’t changed: this remains a $200-million team with World Series aspirations. By winning two straight over the Rays with Wednesday night’s 3-1 victory (in 10 innings), the Yankees stayed 2 1/2 games out of the second wild-card spot.

And as much as the Gallo deal was about this year’s directive, the bonus for Cashman is that he’s signed through next season, too. That means the GM doesn’t have to listen to all this all over again when he puts together his team for 2022. But for the more immediate future, the Gallo trade has changed the narrative for this season -- and could help script a better ending.

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