Guys such as Mike Trout, Mookie Betts and Jacob deGrom don't necessarily need to move over, but they will need to make room for a fresh crop of Major League Baseball superstars in 2021.

Any number of players could make that leap, but we wanted to highlight seven on the young side of the spectrum. These are guys who:

In short, these are guys who are both youthful and on the cusp. Let's give them their due credit in alphabetical order.

Will be 25 or younger in 2021

Already have at least two MLB seasons under their belts

Are making measurable progress toward greatness

Aren't already established superstars, such as Juan Soto or Fernando Tatis Jr.

SP Zac Gallen, Arizona Diamondbacks

Age: 25

Key 2020 Stats: 12 G, 12 GS, 72.0 IP, 55 H, 9 HR, 25 BB, 82 K, 2.75 ERA, 167 ERA+

2020 WAR: 2.7

Zac Gallen wasn't seen as an elite prospect when the Miami Marlins called him up in 2019, so perhaps it's no wonder that they sold high on him while he was sitting on a 2.72 ERA after seven starts.

Well, now he boasts a 2.78 ERA (i.e., a 162 ERA+) through 27 outings after his second season with the Arizona Diamondbacks. And he's only getting better.

Last year saw Gallen finish in the 73rd percentile with both his strikeout rate and his exit velocity. That's to say he was hard to hit in more ways than one, which ultimately speaks to his two primary talents: he lives on the edge of the zone and gets good movement on his four-seamer, cutterand changeup.

Assuming those skills and his health hold strong in 2021, Gallen should net his first All-Star selection and perhaps even make a run at the National League Cy Young Award.

CF Trent Grisham, San Diego Padres

Age: 24

Key 2020 Stats: 59 G, 252 PA, 10 HR, 10 SB, .251 AVG, .352 OBP, .456 SLG, 122 OPS+

2020 WAR: 2.4

Trent Grisham didn't make a great first impression with the Milwaukee Brewers in 2019, slashing .231/.328/.410 in 51 regular-season games and then making a killer error in the playoffs.

Enter the San Diego Padres, who traded for Grisham in November 2019. And their faith in him paid off as he starred on both sides of the ball in 2020.

Defensively, Grisham got the best jumps of any outfielder en route to seven outs above average and a Gold Glove. At the plate, a sturdy .830 OPS against right-handers and above-average metrics—i.e., a barrel rate in the 84th percentile—made him one of the league's more productive center fielders.

At the least, Grisham could be a 20-20 guy and a Gold Glover once again in 2021. Given that he hit 32 home runs in 148 total games between the minors and majors in 2019, he might even have 30-homer potential.

1B Vladimir Guerrero Jr., Toronto Blue Jays

Age: 22 (on Tuesday)

Key 2020 Stats: 60 G, 243 PA, 9 HR, 1 SB, .262 AVG, .329 OBP, .462 SLG, 115 OPS+

2020 WAR: 0.6

After arriving as the No. 1 prospect in baseball, Vladimir Guerrero Jr. disappointed in his rookie season for the Toronto Blue Jays in 2019. And in 2020, his batting average and his on-base percentage decreased.

A 29-point gain in slugging, however, was key in boosting Guerrero's OPS by 19 points. And that gain didn't come out of nowhere, as he dramatically improved both his exit velocity (from 89.4 to 92.5 mph) and his hard-hit rate (38.7 to 50.8 percent).

Guerrero's next improvement must be to his launch angle, lest he hit over half his batted balls on the ground again. That's hardly an insurmountable task, especially knowing that he made strides in the right direction late in 2020.

Factoring in how he's in much better shape than he has been in prior seasons, the signs point toward Guerrero finally realizing his potential as an All-Star and maybe even a batting title contender in 2021.