This early in the season, it's important not to place too much stock in any particular player's strong numbers, especially when it's someone who doesn't have much of a track record at the MLB level.

That said, it is much easier to buy in on an emerging player’s hot start when said player finished the previous season on a high note.

That's the case with these nine up-and-coming stars. All of them showed signs of a breakout in the second half of 2023 and haven't missed a beat in 2024. (All stats below are through Tuesday's games.)

Triston Casas, 1B, Red Sox
Casas’ 2023 rookie season was a tale of two halves -- after entering the All-Star break with a .225/.330/.398 slash and a 97 wRC+, the first baseman was one of MLB’s most productive post-break hitters. Casas homered 15 times after the break and ranked fifth in MLB (minimum 150 PAs) with a 175 wRC+, behind only Shohei Ohtani, Matt Olson, Mookie Betts and Ronald Acuña Jr.

Casas has stayed hot to begin 2024, notching a stellar 144 wRC+ with five homers and 10 walks in 76 plate appearances.

William Contreras, C, Brewers
Receiving his first chance to be a full-time catcher at the big league level following a trade from the Braves to the Brewers in December 2022, Contreras made significant strides on defense but was roughly league average on offense (104 wRC+) over the first three months last season. That changed after the calendar flipped to July, with Contreras recording a .323/.391/.494 slash and a 140 wRC+ over his final 77 games.

The 26-year-old backstop has been even better in 2024, ranking seventh among qualifying batters with a 192 wRC+ while slashing .375/.461/.625 with four homers and 17 RBIs over his first 16 games. Contreras has been blistering the baseball so far, producing hard contact (95+ mph exit velocity) at a 64% clip, the second-best rate in the game.

MJ Melendez, OF, Royals
Melendez was one of the least valuable regulars in baseball (-0.8 WAR, per FanGraphs) during the first half of 2023, combining poor outfield defense with a .206/.289/.333 slash and a 68 wRC+ on offense. However, the former catching prospect made a dramatic turnaround at the plate after retooling his swing during the All-Star break, hitting .273 with 10 homers and a 124 wRC+ in the second half.

Melendez has followed that up by registering a 143 wRC+ through 25 games in 2024, and his current whiff rate (29.4%), strikeout rate (22.4%), walk rate (12.1%) and barrel rate (15.8%) would all be improvements over last season's numbers.

Ryan Mountcastle, 1B, Orioles
Mountcastle has been around for a while and does have a 33-homer season on his résumé (in 2021), but he’s still trying to break into the upper echelon of big league first basemen. The right-handed slugger posted a 113 wRC+ across 2020-23, tying for 18th among qualifying first basemen in that span.

Mountcastle, though, ranks sixth at the position (minimum 200 PAs) with a 150 wRC+ since the 2023 All-Star break. He’s hitting .305 with two homers and a 149 wRC+ over 68 plate appearances this season, and his strikeout (14.7%) and walk (10.3%) rates would both be career bests by a significant margin.

Logan O'Hoppe, C, Angels
Acquired from the Phillies in a 2022 swap for outfielder Brandon Marsh, O’Hoppe began last season as the Angels’ starting catcher and produced four homers with an .886 OPS over his first 16 games before missing nearly four months while recovering from surgery to repair a torn labrum in his left shoulder. O’Hoppe showed some rust in his return to action, going 4-for-36 (.111) in his first nine games after coming off the injured list, but he erupted for nine homers with an .897 OPS in 26 games after the calendar flipped to September and has continued to mash in the early stages of 2024.

The 24-year-old backstop has a .999 OPS and a 191 wRC+ over 56 plate appearances and ranks in the 93rd percentile or better in a number of metrics tracking his quality of contact, including hard-hit rate (96th), expected batting average (94th), expected SLG (93rd) and expected wOBA (94th).

Cole Ragans, SP, Royals
Ragans looked like a potential frontline arm after being traded from the Rangers to the Royals for veteran reliever Aroldis Chapman last summer, and his performance this season has only affirmed his stature as Kansas City’s ace.

The hard-throwing southpaw owns a 1.93 ERA, a 2.35 FIP and an 11.2 K/9 through four starts in 2024, which is more or less in line with what he did over 71 2/3 innings in a Royals uniform last season. Ragans' latest gem against the Mets on Sunday (6 IP, 0 R, 8 K's) saw him record one of the fastest strikeout pitches by a starting pitcher this year, getting Francisco Alvarez swinging on an elevated 100.2 mph four-seam fastball.

Grayson Rodriguez, SP, Orioles
After earning the seventh overall spot on MLB Pipeline’s Top 100 prospects list entering 2023, Rodriguez arrived in the Majors last season surrounded by considerable hype. He found himself back in the Minors after just 10 starts, having posted a 7.35 ERA. However, he has looked like a different pitcher since he returned to the Majors last July.

In 17 starts since the O’s called him back up, the righty has notched a 2.59 ERA with 100 strikeouts and 29 walks in 100 2/3 innings. The Orioles are undefeated in Rodriguez's four starts this season, with the 24-year-old allowing no more than two runs in any of them. Rodríguez’s curveball and changeup have been especially effective so far -- he has limited batters to a .167 average with 14 strikeouts in 38 plate appearances ending on those two offerings.

Tarik Skubal, SP, Tigers
After dominating to the tune of a 2.80 ERA with a 2.00 FIP and a 7.29 K/BB ratio over 80 1/3 innings in his return from flexor tendon surgery last season, Skubal was a popular preseason pick to win the American League Cy Young Award in 2024. The left-hander has only solidified his status as an AL Cy Young favorite with his performance this season.

Going into Wednesday afternoon's showdown against the defending World Series champion Rangers, Skubal had held opponents to the lowest expected wOBA (.200) in MLB (minimum 50 batters faced) while recording a 2.08 ERA with a 20-to-4 K/BB ratio over 17 1/3 innings.

Bobby Witt Jr., SS, Royals
As great as Witt has been since last summer, it's easy to forget that his career didn't get off to the best of starts, with the shortstop recording a .252/.293/.432 slash over his first 252 games in the Majors. Witt, though, has ascended to superstar status in short order. The 2019 No. 2 overall Draft pick hit .323 with 14 homers, 21 steals and a .967 OPS over his final 56 games last season and -- after signing an 11-year, $288.7 million contract extension in February -- has been one of the best hitters in baseball so far in 2024.

Witt has a 1.026 OPS and a 187 wRC+ through 17 games, and he ranks first or second among qualifiers in barrel rate (first at 25%), hard-hit rate (first at 67.3%), average exit velocity (second at 97.6 mph), expected SLG (second at .813) and expected wOBA (second at .501). On top of all that, Witt has become an excellent defender at shortstop, making huge strides after struggling with the glove as a rookie. The 23-year-old seems likely to remain in the AL MVP conversation all year.