Yankees pitcher J.A. Happ throws against the Twins in the...

Yankees pitcher J.A. Happ throws against the Twins in the first inning on Monday, Sept. 10, 2018, in Minneapolis. Credit: AP/Jim Mone

The Yankees’ postseason fate is pretty much settled. Unless something historic happens, they will play the Oakland A’s in the AL wild-card game on Oct. 3.

But which pitcher is going to start that game for the Yankees? There are a lot of factors to consider, including where the game will be played. Here’s a breakdown:

The Yankees held a 1½-game lead going into Saturday in the race for the right to host the game. The teams tied the season series at 3-3. That’s the first tiebreaker if they finish with the same record. Each team won two of three in its own ballpark.

The next tiebreaker is the teams’ records in their own divisional games. Going into Saturday, the Yankees were 35-26 against the AL East. The A’s are 33-34 against the AL West (Oakland played outside the division against Tampa Bay on Saturday). So that tiebreaker looks good for the Yankees.

Two months ago, there would have been little debate. Luis Severino would have started the game, just as he did last season against the Twins. The Yankees won that game despite Severino lasting one-third of an inning and allowing three runs. He was much, much better in his other three postseason starts as the Yankees got to within one game of the World Series.

But Severino has been in a serious second-half slide that has made him the third-most likely pitcher to start the wild-card game. In his last 10 outings, Severino is 3-6 with a 6.35 ERA. That has opened the door for Masahiro Tanaka and J.A. Happ, both of whom are pitching lights out.

So let’s take Severino out of the mix. Forget about the idea that you’ve got to have your ace on the mound in the big game, because Severino hasn’t been pitching like an ace for a long time.

 You’re Aaron Boone. Do you go with the righthanded Tanaka or the lefthanded Happ? And does your decision change if the game is played at the pitcher-friendly ballpark in Oakland instead of the bandbox known as Yankee Stadium?

Let’s look at the numbers (all stats going into Saturday):

First, you have to check if the A’s have a notable platoon split this season. The short answer is no. The longer answer is not really.

Against lefthanded pitchers, the A’s are hitting .245 with a .740 OPS. Against righties, it’s .253 with a .767 OPS. So that’s a small advantage for Happ.

A much larger split for the A’s is their home/road performance. At home, Oakland is hitting .237 with a .721 OPS and 82 home runs. On the road, Oakland is hitting .264 with a .796 OPS and 120 home runs. (But, even with that, the Yankees would still rather play at home.)

Happ is 16-6 with a 3.75 ERA this season and 6-0 with a 2.70 ERA in eight starts since joining the Yankees in a trade with Toronto on July 26.

His only appearance against Oakland this season was a six-inning, one-run performance in a 5-1 Yankees victory on Sept. 4 in Oakland. In his career, Happ is 4-1 with a 3.47 ERA vs. the A’s and 1-1. 4.31 at the former Oakland Coliseum.

As a Yankee, Happ is 4-0 with a 3.45 ERA at home and 2-0, 1.50 on the road.

Tanaka, who is 12-5 with a 3.47 ERA, has not faced the A’s this season. In his career, he is 3-2 with a 2.53 ERA vs. the A’s and 1-1, 4.91 when facing them away from Yankee Stadium.

Tanaka’s last 10 starts have been phenomenal. He is 5-3 with a 2.09 ERA and has thrown scoreless ball in four of those starts, including over 14 innings in his last two outings.

Tanaka’s home and road ERA’s are similar: 3.66 at Yankee Stadium and 3.31 away from it. But he is 5-5 at 11 starts at home and 7-0 in 14 starts on the road. Oddly, Tanaka has given up 15 of his 23 home runs on the road, but he hasn’t lost a game because of it.

Happ has given up 25 home runs. The A’s are a home-run hitting team. Oakland’s 202 are second in the AL to the Yankees’ 236.

What about postseason pedigree? Well, they both have a good one. Tanaka is 2-2 with a 1.44 ERA in four starts.

Happ is 1-1 with a 3.72 ERA in 10 outings (three starts). Happ’s last two postseason appearances were starts for Toronto in 2016. He went 1-1 with a 2.70 ERA.

Remember: You’re Aaron Boone. Who’s it going to be?

How about neither?

This is out-of-the-box thinking, but is it really these days? Maybe the Yankees should use their strength and throw a bullpen game. Chad Green for two innings, Zach Britton for two, David Robertson for two, Dellin Betances for two and Aroldis Chapman for one.

But if they do that and win  . . . who starts Game 1 of the Division Series at Boston?