Darin Ruf can thank the Padres’ abundance of left-handed relievers for his spot on the Mets’ wild-card roster.

The veteran outfielder, who concluded the regular season on the injured list with neck strain, was among the players who presented tough decisions for general manager Billy Eppler and manager Buck Showalter before the deadline at 10 a.m. Friday to submit a roster.

Ruf, who was acquired at the trade deadline from the Giants, had a .152/.216/.197 slash line in 28 regular season games for the Mets.

Showalter said he had expected the Padres to add Sean Manaea as a fourth lefty (which they did) and noted that closer Josh Hader is left-handed.

“This guy has seen a lot of the Padres,” Showalter said of Ruf before the Mets lost 7-1 in Game 1. “You look at some of the history and we think he has done some things. He worked very hard once he got over the neck and seems to be in a good place.”

Not surprisingly, Francisco Alvarez was included on the roster to give the Mets another presence from the right side. It’s likely Alvarez will start at DH in Game 2 against left-hander Blake Snell.

Showalter said he and Eppler also grappled over whether to carry 11 or 12 pitchers (they chose the latter) and how many should be starters. Ultimately, they selected three starters and nine relievers.

Taijuan Walker was considered as an insurance policy, but Showalter said the fact the right-hander just pitched Tuesday left him unavailable for Game 1. The fact the Mets will need a starter Tuesday in the NLDS if they win the wild-card series in three games factored into the decision to exclude Walker.

If the Mets have an emergency, David Peterson, and Tylor Megill can give the team multiple innings from the bullpen, according to Showalter.

Showalter said he and pitching coach Jeremy Hefner contacted players Thursday night to inform them about roster status. The most painful phone calls were reserved for Showalter, who said he had difficult conversations with Walker, Carlos Carrasco and Tommy Hunter, among others, but reminded the players that rosters will be reset if the Mets reach the NLDS.

Alvarez became the youngest Mets player, at 20 years and 322 days, to appear in a postseason game, with his pinch-hitting appearance. Gregg Jeffries previously held the distinction at 21 years and 64 days.

Eduardo Escobar’s solo homer in the fifth ended a 19 inning postseason scoring drought for the Mets since Game 5 of the 2015 World Series. The Mets were shut out in the wild-card game against the Giants in 2016.

Bob Ojeda, a key component of the Mets’ 1986 World Series winning team, threw out the ceremonial first pitch.