NEW YORK -- For the first three months of the season, Luis Severino looked like an ace, the kind of consistently dominant pitcher a team would gladly start in a pivotal, must-win elimination game.

Several hiccups since the All-Star break made him look far different.

But slowly, the New York Yankees' frontline starter seems to be easing back to his old, early-season self as he has begun making his most meaningful starts of the year. He has allowed only two runs across his past two outings.

The good news for the Yankees? Severino isn't the only starter rounding into form.

Trade acquisition J.A. Happ is still undefeated since his arrival in late July, and Masahiro Tanaka, though roughed up Thursday, has been nearly unhittable at times in the past month.

"If we're going to get to where we want to go, all three of those guys you just mentioned are going to play a huge role," Yankees manager Aaron Boone said.

So which one of them will take the mound when the Yankees play in the American League wild-card game?

Within the past week, Boone and his staff have started trying to answer that question. Points and counterpoints have been made, and a host of factors are being considered.

Do you pitch a guy simply because he's the ace? How much credence do you put on recent performances? Does an individual pitcher's postseason history matter? How could planning for the potential Game 1 of the division series impact the decision?

Regardless how the process of picking a wild-card game starter goes, the Yankees believe that with all three pitchers showing flashes of success of late, this choice is one they're fortunate to have to make.

"We're going to have a difficult decision going into that game on who we would use," Boone said. "But also, we feel like we're going to have a really good decision."

Sticking with Sevy?

Until his past two starts, Luis Severino was struggling to prove he deserved to pitch in such an important game.

Since going 13-2 and looking like a firm part of the Cy Young Award discussion through July 1, Severino had posted a 3-6 record entering his start Wednesday against the rival Boston Red Sox. His ERA in that stretch was a bloated 5.72, a stark contrast to his 1.98 mark after the season's first three months.

Prior to turning things around with his one-run, seven-inning outing against Boston on Wednesday and his one-run, 5⅔-inning outing at Minnesota last week, Severino had surrendered six runs in an ugly start at Oakland in which he didn't even make it out of the third inning. He had communication problems that night with catcher Gary Sanchez. The pair recorded two wild pitches and two passed balls in the first inning alone.

But when Boone was asked immediately after that atrocious outing about the possibility of sticking with the battery for the Oct. 3 wild-card game, the manager gave his players a vote of confidence.

"Do I think those two are capable of going out and shoving?" Boone said. "Absolutely."

Boone trusted Severino then, and he certainly does now. The fact the manager was willing to stand up for his ace (and his embattled catcher) after that particularly rough outing shouldn't be forgotten.

"For him, it's just about really getting into a good groove with all his pitches, having the right shape on his slider, and then locating and commanding his fastball," Boone said of Severino. "If he does that, he realizes he's obviously capable, like the elite pitchers in the league, of shutting down anyone.

"And even though he's gone through some ups and downs here certainly in the second half of the season, I really believe he understands that."

Still, these next two starts -- one at Tampa Bay next week and another next weekend in the final regular-season series at Boston -- will be crucial for Severino. If he can prove he is on track following his past two outings, he will have made a case as to why he's the man the Yankees need for the single-elimination postseason opener.

But don't forget, Severino had his chance once before.

While the Yankees ultimately won last year's AL wild-card game over the Twins, Severino didn't perform well. He lasted only six batters, surrendering three runs, allowing four hits and getting only getting one out in the first inning. The bullpen was forced to come to the rescue.

In a game with so much on the line, multiple pitchers could be used again -- regardless who makes the first pitch.

Big-time Tanaka?

Masahiro Tanaka's start Thursday didn't go so well, but his track record in last year's postseason could give him a leg up. Frank Franklin II/AP Photo

Since September began, Masahiro Tanaka had been the Yankees' best starter.

Ahead of his outing Thursday, he had allowed just one run in his previous 21 innings. The way he had been pitching was reminiscent of last postseason, when the right-hander gave up just two runs across 20 innings in his three starts during the ALDS and ALCS.

As reminiscent as those outings may have been, Tanaka took a step backward Thursday. He failed to make it out of the fifth inning in an 11-6 loss to the Red Sox, giving up eight hits, five runs and a home run. It was the first homer he had allowed in five starts.

Still, despite the rough start, Boone will keep Tanaka in the discussion for his wild-card starter.

"We have so much confidence in Masa, especially in a big spot," Boone said Thursday. "So our decision, again, will be hopefully one made from strength. We're deciding between a lot of good options.

"This doesn't make me think he's not going to deliver in a big spot in a play-in game."

A big part of the reason Tanaka has earned a reputation for being a big-game pitcher stems from how he performed in last year's playoffs. When the Yankees needed a win after going down 2-0 to Cleveland in the ALDS, it was Tanaka's seven shutout innings in Game 3 that helped power them to a key victory that turned the series around.

Ten days later, he tossed another seven scoreless in a Game 5 ALCS win that had New York one game away from the World Series. Ultimately, the Yankees lost Games 6 and 7.

Should the Yankees start big-game Tanaka in the wild-card game?

One reason he might not get the ball that night could have to do with how the rotation is currently set. As it stands now, Tanaka is in line to make two more starts, including the regular-season finale at Boston. If he pitches that Sunday, Tanaka would have only two off days before the wild-card game that Wednesday.

Sure, the rotation could change before the final series of the regular season. And even if it doesn't, the Yankees could treat the wild-card game as essentially a bullpen game, using their starter to pitch only a couple of innings, depending upon how he feels and fares.

If rest for Tanaka does play a role in the Yankees' decision, he still could be an option to start the first game of the ALDS. Part of New York's deliberations will include weighing which starter it wants to save for that round.

"You have to strike a little bit of a balance there," Boone said. "But the biggest thing that does come about is that one game, and you're going to do everything you can that you think is right to win that game.

"But for the most part, you're going to pour everything you can into that one game with no tomorrow."

A Happ for that?

Across nine starts since joining the Yankees at the end of July, J.A. Happ is 6-0 with a 2.39 ERA. Brad Penner/USA TODAY Sports

It has been two years since J.A. Happ has started a postseason game. After dealing a pair of highly regarded position players to Toronto in exchange for Happ in July, the Yankees are hoping he'll be making multiple playoff starts this year.

Could the first of those come in the wild-card game?

It seems wholly possible.

When it comes to rest, Happ lines up perfectly. After pitching in the opener of the final regular-season series in Boston on the final Friday of the month, Happ's regular day to pitch would be the following Wednesday; the date of the wild-card game.

Then there's this. As unsteady as Severino and Tanaka have been at times since July, Happ has been considerably more consistent.

Since he arrived in New York on July 26, the southpaw has been undefeated. Across nine starts in pinstripes, Happ is 6-0 with a 2.39 ERA. He also hasn't lost a game at Yankee Stadium since 2014, going 7-0 in that stretch.

That latter stat could be an important one, but only if the Yankees retain their lead in the wild-card standings. Up only 1½ games on Oakland (technically 2½ since they own the tiebreaker), that lead is razor thin. New York also leads the suddenly surging Rays -- a team it visits for four games starting Monday -- by 6½ games.

If the Yankees can keep their lead, the all-important Oct. 3 game would be within the confines of Yankee Stadium, the same place Happ has fared so well.

Assuming the Yankees will face the Athletics, consider Happ's numbers against them this season. In a lone start at Oakland-Alameda County Coliseum earlier this month, Happ tossed a two-hitter across six innings. He allowed just one run to one of the more powerful lineups in baseball.

For his career, Happ is 4-1 against the A's with a 3.47 ERA in 11 games.

So, who starts?

The numbers, it would appear, point to Happ. We'll see if the numbers are enough to sway the Yankees' decision or if the big-game capability of Tanaka, or their loyalty to Severino and his ace stuff, are the deciding factor.

Within 10 days, Boone and his staff will have their answer.