One of the biggest milestone moments in the lead-up to MLB Opening Day is each of the 30 teams naming their starting pitchers for day one of the impending 162-game marathon. For some teams, it's as easy as telling their established ace, “Hey, go get 'em champ.” But in many cases, there are internal debates and questions coming in from the outside about the pitchers getting the ball to open their teams' seasons.

Whether they are first-time MLB Opening Day starters, pitching for a contract, or coming to brand-new environments, there are a number of under-the-radar names taking the mound on Thursday that have everything to prove in their 2024 campaigns. These may not be the top Cy Young candidates as of right now, but they are the starters with most to prove in the upcoming season.

Tarik Skubal, Detroit Tigers

New Tigers ace Tarik Skubal has been one of the darlings of the offseason and with good reason. In just 80.1 innings last season, Skubal racked up 102 strikeouts with a minuscule 0.90 WHIP. Baseball Savant data thinks he was even better, with a league-best 2.30 xERA among all starters with at least 50 innings pitched. If Skubal repeats his performance or is even better over a full season, he'll be in the Cy Young conversation.

That said, Skubal has yet to throw 150 or more innings in an MLB season. At age 27, he's already had his fair share of injury concerns. And if the Tigers are going to live up to their own declared goal of competing for a division title, it's going to rest squarely on this first-time ace to anchor the rotation, with some questionable veterans in Jack Flaherty and Kenta Maeda as his running mates. The stuff is excellent, the recent track record is promising, but we won't know if it clicks until he starts twirling the pill.

Cole Ragans, Kansas City Royals

If Skubal wasn't the trendy left-handed breakout candidate you spent the offseason hearing about, it was Cole Ragans. Used as a reliever in Texas before moving to Kansas City in the Aroldis Chapman trade, Ragans went gangbusters in 12 starts with the Royals, with a 2.64 ERA, 11.2 K/9, and a Pitcher of the Month award for August.

It's one thing to do all that in a soon-to-be-forgotten Royals season that had already lost the plot, but now Ragans comes into the spring with expectations. He gave up some loud contact in Spring Training despite his electric stuff and although K.C. did bolster the rotation behind him, he's the only arm in town with high-end ace potential. How Ragans pitches this season will be a key factor in determining the way the Royals build out their entire roster for years to come.

Shane Bieber, Cleveland Guardians

Cleveland Guardians starting pitcher Shane Bieber (57) bats against the Texas Rangers during the second inning at Surprise Stadium.
Mandatory Credit: Joe Camporeale-USA TODAY Sports

Bet you didn't expect to see a former Cy Young winner on this list, eh? Well, thankfully for the rest of the world, we aren't living in 2020 anymore. Shane Bieber is coming off a year in which he saw career worsts in FIP, K/9 and strikeout-to-walk ratio, plus he missed nearly three months with elbow inflammation. If that isn't enough adversity, he's entering his contract year and has to deal with trade rumors as a constant side effect of his employment with the Guardians.

With all that said, there is a world where Bieber tunes out all the noise and is fantastic this MLB season. It can be great motivation for an established ace to have a young phenom pushing him in the rotation, which is exactly what second-year hurler Tanner Bibee looks to be. Put them together with a hopefully-healthy Triston McKenzie and you have a trio that can compete with the best rotations in the entire league. The Guardians have a sneaky abundance of up-and-coming prospects and if they can compete for the postseason this season, Bieber could pitch his way back into baseball's limelight.

Brayan Bello, Boston Red Sox

There's no sugarcoating things: Bostonians are boiling mad about their team's offseason. They were sold promises of “full throttle” roster additions and instead got an injured 23-year-old second baseman and a starting pitcher who won't be pitching at all this year. But the one day they made their fans unquestionably happy was March 9, when they announced a six-year, $55 million extension for Brayan Bello, in front of numerous friends and family in Bello's home country of the Dominican Republic.

There are tons of reasons to love Bello: he's still only 25, he has rapidly improving stuff and Pedro Martínez has compared him favorably to… Pedro Martínez. For all the talent Bello has, however, it was an up-and-down MLB rookie season in 2023. He got knocked around in his last few outings and ended up with a below-average 4.54 FIP. And the Red Sox made it clear with their refusal to pursue top-end pitchers: they believe Bello is their ace of the future. Whether he proves to indeed be that ace will dictate whether the team with the most championships this century has any prayer of winning another within the next decade.

Tyler Glasnow, Los Angeles Dodgers

Los Angeles Dodgers pitcher Tyler Glasnow against the San Francisco Giants during a spring training baseball game at Camelback Ranch-Glendale.
Mandatory Credit: Mark J. Rebilas-USA TODAY Sports

Would it surprise you to learn that Tyler Glasnow, who was 29 years old last MLB season and began the season still recovering from Tommy John surgery, actually made his career high in starts in 2023? Glasnow took the ball 21 times, shattering his previous high of 14 in 2021, and did what we've come to expect Glasnow to do: strike out 160 batters in 120 innings with a 2.91 FIP. Now, he's in Dodger blue, an almost unheralded addition to the superteam assembled by Andrew Friedman and L.A.'s ownership this offseason. But make no mistake: the pressure is high for the 6'8″ flamethrower.

Though the Dodgers may well have seven or eight quality starting pitchers by the start of the playoff push, Glasnow is the closest thing they have to a known commodity to start the season. Yoshinobu Yamamoto, who they just gave the largest starting pitching contract of all time, has one awful big league inning under his belt. Bobby Miller, Emmet Sheehan, and Gavin Stone? All exciting, but all relatively unproven. Clayton Kershaw, Walker Buehler, James Paxton, Dustin May… all could be huge additions, but none are guaranteed to be healthy at any point.

So that leaves the burden on Glasnow to put up a full, excellent season for the first time ever. For all the superstars the Dodgers possess, he could very well be the one with the biggest hand in determining their ultimate success.