A’s pitcher Liam Hendriks is part of a new strategy that has kept the team in the American League wild-card race. (Thearon W. Henderson/Getty Images)

BALTIMORE — On a Wednesday night in mid-September, in the teeth of a tightening playoff race, on a day when the other American League postseason hopefuls send the likes of David Price, Luis Severino, Carlos Carrasco and Gerrit Cole to the mound, the Oakland Athletics, on a 98-win pace and three games off the AL West lead, will hand the ball in the first inning to a journeyman right-handed reliever named Liam Hendriks and see where it goes from there.

At the direction of a progressive-minded front office, and fostered by a unique set of circumstances — a starting rotation decimated by injuries, plus an expanded September roster that now features a staggering 21 pitchers — the A’s are the latest team to make use of one of the sport’s hot new concepts for pitching-staff management: the “opener,” a short-stint reliever starting the game. The difference is, they are doing so in the heat of a playoff race.

“I’ve seen the success other teams have had” doing it, A’s Manager Bob Melvin said Tuesday. “I’m all for whatever we have the best chance with.”

When Hendriks takes the mound Wednesday at Camden Yards, facing the woeful Baltimore Orioles, it will mark his fourth “start” (with one relief appearance mixed in) in a span of 12 days. He likely will pitch just a single inning, the first, then give way to a more traditional “starting” pitcher, perhaps right-hander Daniel Mengden, who will then seek to carry the game into the later innings where a parade of “relievers” will, in an ideal world, lock down what would be Oakland’s sixth straight win.

These days, it sometimes requires multiple quotation marks to describe pitching roles. And it sometimes requires a noun, such as “bullpen,” becoming a verb, as in: “to bullpen” — loosely defined as, “to cover the nine innings of a game with a collection of relievers and quasi-starters, and in doing so blur the lines between the two.”

The concept, which has been around for decades but typically deployed only in cases of emergency, was popularized this season by the Tampa Bay Rays, who as of Tuesday night had deployed an “opener” 46 times since launching the strategy, largely out of desperation brought about by injuries, in mid-May.

The Rays’ remarkable success — an AL-leading 3.34 ERA since then and a second-half surge that has them, at 79-65, on the fringes of the AL wild-card chase — caught attention across the industry, prompting, for example, the Minnesota Twins to test out the strategy in their minor-league system and teams such as the Los Angeles Dodgers and Toronto Blue Jays to experiment with it occasionally in the majors.

“You can’t argue with Tampa’s success,” Twins Manager Paul Molitor told reporters earlier this season.

At its core, the “opener” concept is merely an extension of one of the game’s clear trends in the second half of this decade: the slow erosion of the line separating starters and relievers in the age of analytics. As starters’ percentage of overall innings declines to the lowest point in history — just 61.9 percent in 2017 — and bullpens grow in importance, we are creeping toward a time when all pitchers are interchangeable and traditional roles are nonexistent, with everyone deployed in short-burst, high-velocity stints based on situations.

While there will still be gifted starters who pitch deep into games, the days when, for example, a Max Scherzer/Aaron Nola matchup might draw you to the ballpark could be dwindling. This is not a notion that will thrill traditionalists already unhappy with a game that has become increasingly reliant on strikeouts, defensive shifts and pitching changes at the expense of balls in play and quick pace.

Oakland Manager Bob Melvin has made more pitching changes than usual over the past month. (Photo by Thearon W. Henderson/Getty Images)

The concept has other unintended consequences, one of which has already been voiced by a handful of pitchers concerned about its effect on the game’s salary’s structure. For starting pitchers, their compensation, via arbitration and free agency, has traditionally been based heavily on factors such as innings pitched and number of starts made.

“The main problem I have with it,” Arizona Diamondbacks veteran Zack Greinke told Bleacher Report, “is if you do it that way, then you’ll never end up paying any [pitcher] what he’s worth because you’re not going to have guys starting, you’re not going to have guys throwing innings. You keep shuffling guys in and out constantly so nobody will ever get paid.”

Even within the A’s clubhouse, toward the end of a season in which 10 starting pitchers have been lost to injuries, the notion of an opener required a bit of a sales job to get the players on board.

“The first one,” Melvin said, “was a little odd for us, because we hadn’t done it before and it was a little different than anything we’d done. … It’s just [a matter of] getting used to it and communicating with the guys when they’re going to pitch and understanding this is the direction we’re going.”

It’s difficult to argue with success. Since Sept. 1, the first time the A’s deployed Hendriks as an opener (and lost), they are 7-2 and have all but locked down a playoff spot, pulling within striking distance of the Houston Astros in the West and the New York Yankees in the race for the first wild card. The A’s expect to use an opener at least once each turn through their rotation through the end of the season.

“We’re going to do whatever we need to do to win ballgames,” said Jonathan Lucroy, Oakland’s veteran catcher. “If that includes a bullpen day, a [starter] coming in [the game] in the second or third inning to eat up innings, that’s what we’ll do. We had no other choice. It’s not the ideal situation, but we had to adapt and overcome.”

Although the A’s speak as if their rash of pitching injuries — with nominal ace Sean Manaea the latest to be lost for the season — has forced them to adopt the opener strategy, that’s not entirely true. The starting pitcher who has followed Hendriks into the game for what is typically a three- to five-inning stint could just as easily start the game, with Hendriks pitching in a more traditional middle-relief role.

The opener, in fact, is rooted in another analytics-driven concept. Because a lineup’s best hitters are typically stacked at the top — and the first inning is the only inning where they are guaranteed to come to the plate — it makes sense to deploy an “opener” (the identity of whom can be based on matchups) against them in the first, then let a “starter” take over against the bottom half of the lineup in the second, reducing the number of times he has to face an opponents’ top hitters.

With the A’s closing in on a wild-card berth — in plenty of time to set their rotation the way they wish — it isn’t out of the question that they might “bullpen” the wild-card game. Their likely opponent, the Yankees, essentially did that a year ago, when Severino, their starter, lasted just a third of an inning, requiring four relievers to piece together the remaining 26 outs in an 8-4 win over Minnesota.

Later that fall, the Astros famously won the World Series while shuttling nominal starters between the rotation and the bullpen, closing out the ALCS with Lance McCullers and the World Series itself with Charlie Morton, neither of whom had pitched in relief a single time during the regular season.

And if the A’s succeed for the rest of September and (especially) deep into October while deploying an opener every few games, you can be certain of one thing: The rest of baseball will be quick to follow, and the days when pitching staffs are divided into starters and relievers will be numbered.

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