It gets lost in time, but Masahiro Tanaka initially was exactly what the Yankees envisioned after investing $175 million (including a $20 million posting fee to his Japanese team) to land him. He opened the 2014 season 12-4 with a 2.51 ERA, averaging better than a strikeout an inning, parking behind perhaps only Seattle’s Felix Hernandez and the White Sox’s Chris Sale at midseason in the AL Cy Young chase.

Then a small tear in his right elbow was discovered.

The fear — and it would linger beyond 2014 — was Tommy John surgery would be needed. Which makes what he has become ironic. Tanaka never again was the consistent high-end ace of the 2014 first half. But he has become among the game’s more durable starters.

He is 22nd in the majors in starts since 2015, 20th in innings, and even with the abbreviated 2014 he joined Andy Pettitte (nine years 1995-2003) and Fritz Peterson (eight seasons 1966-73) in making at least 20 starts in each of their first six Yankee seasons. Start 27 of 2019 came Tuesday night — seven shutout innings in Seattle — a total he has reached now in each of the last four seasons.

This year, even while fighting to rediscover his signature split amid problems with the seams on the 2019 baseball, Tanaka has remained a strong mid-rotation piece. His stats are distorted by two horror shows against the Red Sox (18 runs/four innings).

But he also has as many starts of six innings (19) as Jacob deGrom and as many of seven innings and one or no runs (five) as Clayton Kershaw and Stephen Strasburg. And we will soon see if he can extend his postseason excellence (1.50 ERA in five starts).

We also will soon see if the Yankees and Tanaka have extension plans. Tanaka is due $23 million in 2020, the last on his seven-year deal. He turns 31 on Nov. 1. If the Yanks believe in the sturdiness of the elbow then Tanaka — unfazed by all things Yankees — should be a serious extension candidate. CC Sabathia is retiring. J.A. Happ and James Paxton are free agents following the 2020 season (perhaps Paxton is an extension candidate too). Is Tanaka the steadying influence to keep around Luis Severino, Domingo German, Jordan Montgomery and whomever might emerge from a prospect group that includes Albert Abreu, Deivi Garcia, Luis Gil, Michael King, Jonathan Loaisiga, Luis Medina and Clarke Schmidt?

Will the Yankees pursue Gerrit Cole in free agency? Lots of teams will. He will cost big, and even if the Yankees get him it will push them to luxury tax places they don’t want to be, especially if they also want to retain free agents Didi Gregorius and Aroldis Chapman (who can opt out). So extending Tanaka could lower his hit toward the luxury tax payroll, currently $22.143 million for 2020.

Tanaka has statistical similarity to Lance Lynn going into his free agency last offseason when the righty got three years at $30 million from Texas. Tanaka is a year younger and perceived better. But he seems to love being a Yankee and might not want to go out into free agency after 2020 hitting 32 and with questions anew about the elbow. So could the Yanks tack on three years at $37 million to the pre-existing $23 million and create a new four-year, $60 million dollar deal that would lower his hit toward the payroll to $15 million a year?

That sounds reasonable for a durable, dependable starter.