Three years ago Jordan Montgomery came from far off the pace to win the final spot in the Yankees’ rotation, then impressed in the first taste of the big leagues.

A 9-7 ledger with a 3.88 ERA in 29 starts at 24 years old provided a glimpse of what the 6-foot-6, 228-pound left-hander could develop into.

Now, after Tommy John surgery in 2018, when he was limited to six starts at the beginning of the season and working in two September big-league games late in 2019, Montgomery enters spring training as the betting favorite to cop a rotation spot that opened Wednesday when James Paxton underwent back surgery that could keep him out through May.

Joining Montgomery in the field of candidates are Luis Cessa, Jonathan Loaisiga, Mike King and longshot Deivi Garcia, the Yankees’ top pitching prospect.

“He has good stuff, he battles out there and attacks the strike zone,’’ an NL scout said of Montgomery. “Pre-surgery he and King had the best command. They throw a lot of strikes.’’

With 36 major league starts, Montgomery has more starting experience than the other four combined. Of Cessa’s 86 outings, 19 have been as a starter, though his 232 big-league innings lead the group. Loaisiga has started eight of 24 games. King, who was sidelined early last year with a stress reaction in the right arm, made his major league debut late last season in relief and Garcia hasn’t pitched above Triple-A.

With that kind of depth, the Yankees don’t look as if they will need to use an opener as much as they did last year when reliever Chad Green made 15 starts.

Aaron Boone didn’t establish a leading candidate for the fifth spot, but spoke highly of Montgomery on Thursday at the Yankees’ minor league complex in Tampa.

“I think he has proven himself at this level. For him to get back last year was big, just for his frame of mind,’’ Boone said. “The fact he was able to make it back and get some work done, get into some games, I think was big for him and his mindset moving forward.’’

Despite the edge in starting experience and the success of 2017, Montgomery is locked into the mindset he carried three years ago.

“I’ll treat it like 2017. I’ll do my best to compete. Things always happen, so the more arms you have the better. I’ve got to be ready,’’ Montgomery said this week in Tampa. “I just want to pitch and be healthy. Whatever the Yankees need, I’ll bring something to the table. I had a normal offseason, finally. Good to get home and just work out and throw. I feel pretty strong right now. It’s good to have a new arm.’’

As for the 20-year-old Garcia who dominated at Single-A and Double-A but struggled at Triple-A, Boone pointed out Garcia is young and about to experience his first big-league camp.

“I don’t want to put anything on anyone. These things will kind of declare themselves. Bottom line is Deivi is someone we’re very excited about. … We’ll try to get him in the best position to be successful and potentially impact us,’’ Boone said. “I don’t want to put any expectations on him right away. It is his first camp, he’s got a really bright future and we’ll see where it leads.’’

Boone said he hopes Paxton’s back surgery repairs the problem for good and saves the veteran left-hander’s best for the latter part of the season.

“Hopefully this is what knocks it out for good and puts it past him and he ends up saving his bullets for the end,’’ Boone said. “Feel good about the surgery and look forward to him being back soon.’’