PORT ST. LUCIE, Fla. -- Talk to an evaluator for a few minutes at Mets camp, and invariably the conversation will shift to the team's pitching depth. While the general population may have concerns about what lies beyond the Mets' top four starters, the front office and coaching staff are smitten with the other arms in-house.

Manager Mickey Callaway said this week that the team will not stretch out Seth Lugo or Robert Gsellman as starters, leaving about a half-dozen options in camp after Jacob deGrom, Noah Syndergaard, Zack Wheeler, Steven Matz and Jason Vargas. Two of them, Walker Lockett and Hector Santiago, pitched Saturday in the Mets’ Grapefruit League opener against the Braves, with Lockett allowing two runs and three hits in 1 2/3 innings and Santiago working around a walk in a scoreless third inning. The others will take what opportunities come throughout the spring.

“I’m really curious about it,” Callaway said. “It’s hard to get out of Spring Training with a healthy rotation. So I’m really excited to see those guys really competing for a spot in our rotation. It’s not just, ‘I’m going to show them what I can do so I can be the first guy called up.’ They understand that things happen, and they’re going to do everything they can to be in the rotation on Opening Day.”

Here’s a look at that rotation depth, in rough order of how likely the pitchers are to start games this season:

Walker Lockett, RHP

By his junior year of high school in Jacksonville, Fla., Lockett was already around 6-foot-3, two inches shy of his present height. But the Providence School’s basketball team, which featured future Division I talents like Grayson Allen, had little need for another frontcourt player. Lockett was more interested in baseball, using his height to create difficult angles for hitters.

It was enough for the Padres to draft Lockett in the fourth round in 2012, shepherding him through their Minor League system for seven seasons. Lockett finally debuted last June and appeared in four games for the Padres, who -- due to a 40-man roster crunch -- traded him to the Indians after the season. Two months later, Cleveland flipped him to the Mets for catcher Kevin Plawecki. Because Lockett has Minor League options remaining, he’s likely to begin this year at Triple-A Syracuse. But he is a strong bet to start games later this summer.

“You don’t ever really expect to get traded, so when it happens two times in an offseason, you just don’t really know what’s going on,” Lockett said. “But any time a team trades for you, you feel good about it.”

Hector Santiago, LHP

Growing up a Mets fan in Newark, N.J., Santiago regularly attended games at Shea Stadium. So when Mets general manager Brodie Van Wagenen came calling this winter, Santiago said, “I’m in.”

“I always told me wife and family members I would like to, at some point in my career ... go back and play at home,” Santiago said. “I always rooted for the Mets to give me a call.”

Like Lugo, Santiago boasts experience as a starter, a long reliever and even a closer, doing it all last season for the White Sox. With that skill set, he stands a strong chance of making the Opening Day roster as a left-handed reliever alongside Justin Wilson -- and the Mets have reason to keep him around, considering what he also offers the rotation in terms of depth.

The catch? Santiago has multiple outs in his Minor League contract. If he doesn’t feel he’ll make the team, he may seek better opportunities elsewhere.

Corey Oswalt, RHP

The Mets’ sixth starter last year, Oswalt remains very much in the mix in 2019. While Mets officials consider him a tick behind Lockett and Santiago on the depth chart heading into Spring Training games, they are intrigued by what Oswalt showed down the stretch last season. Finally given a chance to start on a regular schedule in September, he posted a 3.07 ERA over his final four starts.

Drew Gagnon, RHP

By the end of last season, Gagnon’s four-seam fastball was sitting more regularly in the mid-90s, offering the Mets a glimpse of his untapped potential. Already 28 years old, Gagnon is not a prospect in the traditional sense. But like last year, he stands a good chance of starting a game (or two, or three) this summer.

Chris Flexen, RHP

After dropping 30 pounds thanks to an improved diet and fitness regimen, Flexen defined this spring as “career check time.” To date, he has produced an 8.45 ERA over 10 big league starts and eight relief appearances. He hopes better conditioning will allow him to become a more permanent fixture on the 25-man roster.

Kyle Dowdy, RHP

Because they must offer him back to the Tigers for a nominal fee if he does not make the team, the Mets will give Dowdy, their Rule 5 Draft pick last December, every opportunity to break camp with the big club. Team officials have been impressed with the sink on his fastball, as well as his off-field makeup that Callaway considers off the charts.