With Major League Baseball's 2021 Draft kicking off on Sunday, this week's Prospect Watch is dedicated to highlighting four of the class's most polarizing players who are expected to be selected during the early rounds.

"Polarizing," to be clear, does not mean that these players are bad; nor does it mean that these players have no shot at productive big-league careers. Rather, it just means that these players inspire a wide range of evaluations, based on the recent conversations CBS Sports has had with scouts and analysts.

With that in mind, let's highlight the four players and explain why there's uncertainty surrounding their games.

Kumar Rocker, RHP, Vanderbilt

Rocker is the most famous player in the class. He earned that distinction in part by striking out 19 batters in a no-hitter against Duke back in the 2019 postseason. He was 19 years old at the time. Rocker has since wrapped up his storied career at Vanderbilt, finishing with a 2.89 ERA and a 4.72 strikeout-to-walk ratio in 42 appearances. How, then, does such an accomplished performer find himself on a list like this one?

A reasonable explanation has Rocker's prominence working against him, in a sense, by leading to overexposure. Teams have been dissecting his game for more than two years now, giving them ample time to key-in on and magnify his blemishes. We covered many of the perceived negatives to his game when we ranked him as the No. 8 prospect in the class:

Rocker is as physical as they come (he's listed at a Brad Keller- or Lance Lynn-like 6-foot-5, 245 pounds), and he possesses one of the draft's best chase pitches, in his trademark slider. Alas, there are several reasons he could drop outside of the top five, beginning with a velocity dip he experienced earlier this year. Rocker's changeup is underbaked, and scouts are concerned that his arsenal will play lighter than it should against big-league hitters. His mechanics, specifically a high elbow and an oft-late arm, are worrisome as it pertains to his command and durability. Rocker should still go in the top 10, and there's a chance he makes the skepticism look misplaced in due time.

Rocker still seems likely to come off the board within the top 10 picks. It's difficult to find a fit for him in the top five, however, and that clashes with the public perception of him as an elite, can't-miss prospect. 

Jud Fabian, OF, Florida

Fabian, another SEC performer, entered the preseason ranked as the best collegiate hitter in the class. He's since had his stock slip after a season in which he struck out in 29.3 percent of his plate appearances. (He also hit .249/.364/.560 with 20 home runs.)

The hit tool, or the ability to produce average, is still regarded as the most important of the five scouting tools. Players who run high strikeout rates, particularly in college or at the lower levels of the minors, are always going to engender doubt as to whether they'll be able to produce a high enough average in the majors to buoy their on-base and slugging percentages. 

When teams are evaluating the hit tool, they're really evaluating a number of attributes, including a the adaptability of a player's swing (if it's grooved or if they can hit pitches all over the place); their feel for the barrel (how often their contact qualifies as quality); their approach; and so on. It's a complex matter, but those traits help to inform the players' power and on-base abilities, too.

At the risk of oversimplifying the whole thing, Fabian's draft candidacy comes down to if teams believe he can develop a 45-hit tool versus a 40-grade hit tool -- or, statistically, about 10 points of batting average. Here's what we wrote when we ranked him at 41st in the pre-draft list:

Fabian entered the season ranked as the third-best prospect in the class. He had an impressive track record against SEC competition; he was young for a college junior; and scouts foresaw him having plus power. Then Fabian, a wrong-way guy (he bats right, throws left), went … well, the wrong way. He punched out in 29.4 percent of his regular season plate appearances, including 36 percent of those he took in February and March. He made several mechanical tweaks thereafter, and he went on to strike out at a more modest clip (24.7 percent) the rest of the way. Teams won't be running pell-mell in Fabian's direction, but a club who believes his hit tool can approach fringe-average could pop him before the end of the first round.

There's a belief within the industry that Fabian could sneak into the first round, landing with the Los Angeles Dodgers at pick 29. It's to be seen how much of that rumor is smoke versus fire, but it stands to reason that some team in the 25-to-45 range will view Fabian as a worthy upside play.

Jackson Merrill, SS, Severna Park HS (MD)

Merrill is one of the late risers in the draft process. He checked in at No. 50, the wild-card spot, in our pre-draft list. We explained the evaluative conflict for him as part of his capsule:

Merrill is a risk-reward play for the final spot on this list. He's moved up boards quickly over the last month, though estimates on where he'll go in the draft are all over the place. His boosters see him as an above-average hitter, complete with good pop from the left side, whereas his detractors would like to see him go to Kentucky and prove that he isn't the product of facing Maryland high schoolers. However Merrill's career plays out, he's likely to be one of the most second-guessed selections in this class.

Predictably, the industry has provided a laughably wide range on potential landing spots for him. At minimum, he's certain to go much, much higher than anyone would've thought two months ago.

Brody Brecht, RHP, Ankeny HS (IA)

We'll end with another late-rising riddle of a player in Brecht, who did not make the cut for the top 50. He's a 6-foot-4 right-hander with a steep release point from which he throws an upper-90s fastball and a promising slider. He also has a commitment to play wide receiver at the University of Iowa. 

Teams are working with limited looks and impressions of Brecht, meaning his expected landing spot is all over the place. A team that believes in his (however raw) ability and his signability could pop him earlier than expected to snatch him away from the Hawkeyes.