JUPITER, Fla. -- Last spring, Jose Martinez slugged his way from obscurity and onto the Cardinals' Opening Day roster. Jeremy Hazelbaker enjoyed a similar ascension the spring before.
With Grapefruit League action set to open on Friday at Roger Dean Stadium against the Marlins, which dark-horse candidates emerge this year? Rookie right-hander Jack Flaherty takes the ball at 12:05 p.m. CT with a chance to crack the back end of the rotation -- but he's not necessarily a dark horse. We'll save that distinction for players without any big league service time.
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Let's take a look at some under-the-radar options the Cardinals could bring with them to New York for Opening Day.

RHP Conner Greene:  Acquired from the Blue Jays in the Randal Grichuk trade, the 22-year-old Greene sports a fastball that can reach triple digits. But like many young hard-throwers, Greene has struggled with command throughout his Minor League career. Walks were an issue again last season, when he staggered as a starter at Double-A.
Polish- and status-wise, Greene may be behind other young, hard-throwing options in camp. But he's the only one already on the 40-man roster. That alone will earn him an extra-long look, probably as a reliever.
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UTIL Breyvic Valera:  Valera got 10 at-bats with the big club last September, so he's the exception to our service-time rule. But, as a perpetually overlooked player with little power, he counts as a dark horse. The slap-hitting switch-hitter is on the 40-man, which gives him an inside track at Opening Day after eight Minor League seasons. The Cardinals like his versatility (experience at six positions) and how his high contact rate foils in today's high strikeout environment.
OF Adolis Garcia: Valera only sneaks onto the club if the Cardinals choose to break camp with 12 pitchers, not 13. That would leave five bench spots, three of which are already accounted for by Carson Kelly, Martinez and Greg Garcia.
With two spots to play with, the Cardinals would prefer to bring another infielder and a fourth-outfielder-type north. If they have just four bench spots, the priority will go to the outfielder.
That's where Garcia comes in. Signed as an international free agent last spring, the strong, speedy Garcia enters this one behind Harrison Bader and Tyler O'Neill on the depth chart. But he could leapfrog them with a Grapefruit League showing like his first season in pro ball, when Garcia hit .290/.340/.476 with 15 home runs and 15 stolen bases across two levels after defecting from Cuba. The soon-to-be 25-year-old would have to be added to the 40-man roster, unlike Bader and O'Neill.
RHPs Jordan Hicks, Ryan Helsley, Dakota Hudson:  These three are often packaged together for marketing and alliterative purposes -- but also because they could all factor into the Cardinals' bullpen at some point this season.
Whether that's Opening Day will hinge on a variety of factors, including how the three young righties perform this spring, how uncertain the Cardinals consider their late-inning options in a month, and the health of Alex Reyes.
Hudson (seven starts) and Helsley (one) got a taste of Triple-A last season at age 22. Helsley's high-octane stuff profiles particularly well in the bullpen, at least in the short-term.
The same is true for Hicks, who at age 21 is the least advanced of the group. He's already turning heads in camp thanks to a four-seam fastball that can hit triple digits. But the club could feel he needs more seasoning after struggling as one of the younger players in the Arizona Fall League.
"There's not a question of talent," Cardinals manager Mike Matheny said. "I think there are a number of kids in here with the exact same story. But I think sometimes we've got to pump the brakes. Stuff, all by itself, isn't going to be enough to help a guy have success here, otherwise he would have dominated every place he's ever been."
Helsley's age and ability to miss bats probably gives him the best shot at breaking camp in the group. All three would need to be added to the 40-man roster.