Fantasy Baseball 2021: Highlighting Top Sleepers for MLB Week 22

September is the hardest month to navigate in fantasy baseball. 

The margin of error in head-to-head leagues is slim, with the fight for playoff positioning coming down to the wire. 

The added dynamic of players being called up to the major league roster can help or hurt you depending on which names are involved in the matchups.

On Wednesday, Major League Baseball rosters will expand to 28 players. Some top prospects have already been called up to fill the extra spots. 

A handful of intriguing pitching prospects were brought up to the majors right before the September 1 expansion, and they could also play a major role in flipping matches. 

The other complication is the presence of COVID-19 within a few clubhouses. The Boston Red Sox are the team most affected by an outbreak right now. The healthy players on their roster may be worth waiver-wire pickups because they will have to fill roles left open by those unavailable to take the diamond. 

According to Ken Rosenthal of The Athletic, the Toronto Blue Jays are calling up Nate Pearson as part of their roster expansion.

The right-handed hurler will be one of the highest-rated prospects to get the call to the majors in September. He is the No. 43 overall prospect in baseball, per MLB.com's Top 100. 

Pearson is the top pitching prospect in the Blue Jays' system and should provide a boost to the staff in whichever capacity he is called upon. 

The 25-year-old made one appearance this season for the Blue Jays before he was sent back down to Triple-A Buffalo. After a two-month injury layoff, he returned to pitch six one-inning outings in Triple-A to build back his in-game fitness. 

Pearson conceded two earned runs on three hits and struck out eight batters in his six frames from August 14-31. He will likely be used out of the bullpen to start since the Blue Jays have five established starters in their rotation right now. 

He could bridge the gap between the starters and the back-end relievers. If he performs well in his first few appearances, he could earn a greater role in the final two weeks of the regular season.

The Odessa, Florida native is a low-risk, high-reward waiver-wire pickup right now since he is widely available in Yahoo fantasy leagues. 

If Pearson thrives in his first week back in the majors, his roster percentage could go up as a player who chips in strong one-inning outings. 

Edward Cabrera made his MLB debut on August 25 for the Miami Marlins. 

In two starts, the right-handed hurler conceded six earned runs on 11 hits, but he only walked three batters. Those numbers aren't awe-inspiring, but he has the potential to get better with every September start. 

Miami will not be playing in any high-pressure games, which should allow Cabrera to work through any issues, but his fantasy intrigue comes from a favorable schedule that takes up the middle part of this month. The Marlins play the Washington Nationals and Pittsburgh Pirates for nine straight games from September 13-22. 

Before then, they have one series each with Atlanta and Philadelphia, as well as three home games with the New York Mets. 

After Thursday's game in New York, Miami plays 12 of its next 18 games at home. That should help Cabrera feel more comfortable and settle into a pitching rhythm. 

At the minor league level, the 23-year-old had a 3.68 strikeout-to-walk ratio and a 2.93 ERA over 13 appearances at three levels. 

If the strikeout ability shows up to pair with his low walk total, Cabrera could turn into one of the fantasy surprises of this month.

Adam Ottavino should receive most of the high-pressure innings out of the Boston bullpen over the next few days, with closer Matt Barnes and others on the COVID-19 list at the moment. 

Ottavino is coming off a strong August in which he conceded two earned runs over 10 innings. He has not allowed a run in his last six trips to the mound. 

The right-hander's consistency out of the bullpen should pique the interest of any fantasy players in need of help in the relief-focused stat categories. If he extends his scoreless run into September, he could help lower your team's ERA and pad the saves or holds categories. 

The 26-year-old could still be a solid waiver-wire pickup for September when Barnes returns because he has been such a reliable arm out of the Boston bullpen lately. 

If Boston wants any hope of getting into the postseason, it will need Ottavino and other back-end relievers to be at their best for the entire month. The team's playoff chase could also lead to more appearances for the New Yorker, who has 56 strikeouts in 56 innings this season.

Statistics obtained from MLB.com.