By Joe Sparacio

This year, we have seen some truly promising youngsters look ready to make the leap and join the game's elite pitchers. I have already covered James Paxton, the fireballer in Seattle who is taking over the reins from Felix Hernandez. But here are five more aces in the making whose jerseys you may want to buy before they win their first Cy Young Award.

Lance McCullers

McCullers, 23, is on the disabled list because of back soreness, but he is supposedly on the shelf for only a short time. That's good news for the Astros, as he has not only been one of the best pitchers on their team but also one of the best pitchers in the Majors.

In general, McCullers may be the closest to "acehood" already on this list, as he is at the top of MLB player rankings and possesses absolutely filthy stuff. Entering the season, many recognized the power pitcher's ability to strike out batters and ESPN even named him as a dark horse in the American League Cy Young Award race. As it turns out, they weren't far off.

McCullers' ability to get batters to swing and miss rivals that of aces like Chris Sale and Max Scherzer. Entering the weekend, McCullers was sixth in the league in ERA (2.58), has a WHIP of 1.06 (one percentage point below Stephen Strasburg) and boasts a K/9 of 10.45 -- which is actually above that of Strasburg. What's more is that he has a .875 winning percentage, which is second-best in the league only behind undefeated teammate Dallas Keuchel.

What's his secret weapon? An absolutely devastating curveball. The pitch is so nasty that it actually made the cover of Sports Illustrated..

Robbie Ray

In 2014, Ray had an 8.16 ERA with the Detroit Tigers, and as a 12th-round pick, he seemed closer to being out of the game altogether than becoming an effective pitcher. Even last season, Ray posted a 4.90 ERA and accumulated 15 losses, numbers that you might expect out of a swingman in the rotation on the brink of getting demoted to the Minors.

But something happened last year with the D-backs that made everyone think twice about the 25 year-old Ray: He began striking guys out at an insane rate. Despite his high ERA, he posted an 11.3 K/9 and as a result, he registered the fourth-most strikeouts in the National League in only 171 innings -- topping guys like Noah Syndergaard and Jake Arrieta. Looking back it may have actually been one of the great feats in history. The underlying numbers like FIP painted a far better picture of the southpaw's future, and this season, that's come to fruition. He's now shown that he has the stuff to be a frontline pitcher.  

Ray is tied for second in the NL in strikeouts, but this now comes with a 2.62 ERA heading into the weekend, trailing only Scherzer and Clayton Kershaw. Ray has also given up only eight home runs on the season. At one point, he even had a scoreless streak going of 27 2/3 innings, a mark that trailed only Brandon Webb in franchise history.

Carlos Martinez

Martinez has been very good over the past two seasons, but in 2017 he has made the jump. The right-hander's name is all over MLB leaderboards: He is tied with Ray for the second-most strikeouts in the NL, has held opposing batters to a .195 average against him and has a 2.86 ERA, good for seventh-best in the NL. Need further proof that he has some of baseball's best stuff? Martinez struck out baseball robot Joey Votto on a pitch that was so good that it actually made the Reds' slugger laugh.

All in all, Martinez is looking like the Cardinals' leading All-Star candidate this season and is proving that his dominance the past two years is no fluke. He threw his first career shutout this season as well, showing that his velocity and effectiveness don't slow down in later innings, something that analysts had been worried about in the past. Martinez is only 25 years old, and it looks like we may be seeing what he can do as he enters his prime.

Luis Severino

All eyes have been on Aaron Judge in pinstripes (and rightfully so), but young Severino has quietly been dominating the American League at the same time.

Severino's 2.99 ERA slots in right between Yu Darvish (3.03) and Sale (2.82) in the AL leaderboard. His 1.05 WHIP is fifth-best in the AL, between Carlos Carrasco and McCullers.

Last season, Severino posted a 5.83 ERA and was demoted to the Minors to work on harnessing his stuff. What changed? Well, Severino worked hard and refined his arsenal. Fangraphs breaks it down well, but in essence, Severino has increased the gap in velocity between his fastball and his offspeed stuff, developed his slider into a swing-and-miss pitch and is generating a lot weaker contact and ground balls.

At 23 years old, we probably haven't even seen Severino at his best yet, and with even more time to develop and further tinker with his breaking pitches, he may quickly become one of the best pitchers in the game.   

Michael Fulmer

After Fulmer posted a 3.06 ERA and 1.19 WHIP for the Tigers in 2016, narrowly beating out the Yankees' Gary Sanchez in AL Rookie of the Year Award voting, some expected his numbers to regress. He has proved the critics wrong.

With typical Tigers ace Justin Verlander struggling, Fulmer has largely carried the load for his team. He has posted a 3.45 ERA (and an even lower 3.04 FIP) this season, along with a 1.19 WHIP, and he has been able to suppress homers this year, allowing only one home run every 18 innings on average (good for the best mark in the league entering the weekend).

Fulmer has been the sixth-most valuable pitcher over the past year -- plus, you know that when you have a bearded bobblehead, you've made it big. When you can dial it up to 99mph and have great offspeed stuff to boot, your foundation to become an ace is basically as good as any.

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Joe Sparacio is an associate producer for Sports on Earth. Follow him on Twitter @joetsparacio.