The 2020 college football season was unlike anything seen in more than 100 years. With COVID-19 being a heavy influencer, college football looked vastly different and the effects of the coronavirus will hang over the sport for years to come. One of the byproducts of the virus was the NCAA allowing an extra year of eligibility for those players who wanted it. Another was the willingness by some players to opt out early and declare for the draft. 

The deadline for underclassmen to declare for the 2021 NFL Draft has come and gone, while the official list of early entries will be released at the end of the week. Players leaving early for the NFL Draft is a double-edged sword. On one hand, it can be the best business decision available and it's something schools have bought into over the past several years. 

On the other hand, it can be tough to reload every single year as some teams are hurt way more by losing underclassmen early. Though roster turnover is a part of life for every school, these ones in particular find themselves with plenty to replace in 2021. 

The tone of Penn State's 2020 season was set before a snap was played when star linebacker Micah Parsons opted out. Losing freaky athletic defensive end Jayson Oweh and tight end Pat Freiermuth now are big blows, too. Parsons and Oweh are likely first-round picks and Freiermuth will be one of the top tight ends in the draft. While the departures were expected, they were still some of Penn State's best players.
Despite some notable roster attrition over the past year via the transfer portal, the Cardinal had a decent 2020 season. They won four straight games to close out the year while overcoming numerous COVID-19 hurdles that took them away from Palo Alto. Still, the list of early entrees in the draft makes Stanford one of the hardest-hit programs. Cornerback Paulson Adebo is the biggest name -- he was a preseason All-American -- but quarterback Davis Mills and top wideout Simi Fehoko are notable losses, too. Center Drew Dalman was a team captain and an All-Pac-12 selection. 
Georgia returns a pretty good core of players for 2021 to make a run at the SEC East title, but not without losing a few big-time defenders. Linebacker Azeez Ojulari as well as cornerbacks Tyson Campbell and Eric Stokes are entering the draft. Stokes was an All-America selection, and Campbell and Ojulari were key members of a defense that finished in the top 10 nationally in yards per play allowed. The Bulldogs have been recruiting at an elite level to rebuild after departures like these, but that's three all-conference-caliber players moving on. 
The exodus of Texas players began once it became clear the Longhorns would not be playing in the Big 12 Championship Game. The least surprising departure announcement is defensive end/linebacker Joseph Ossai, who led the team with five sacks. He's a high-motor athlete who's going to carve out a great NFL career. Top offensive lineman Samuel Cosmi, wide receiver Brennan Eagles and defensive back Caden Sterns have also declared. There's not any Day 1 talent outside of Ossai, but Cosmi and Sterns could be good pickups and Eagles is an intriguing pro prospect.
In sheer volume alone, USC is one of the hardest-hit teams with seven underclassmen leaving early. CB Olaijah Griffin, S Talanoa Hufanga, WR Amon-Ra St. Brown, DT Jay Tufele, DT Marlon Tuipulotu and OT Alijah Vera-Tucker are all moving on. The loss of St. Brown, along with senior Tyler Vaughns, leaves some big shoes for Drake London and Bru McCoy to fill, but they have the size and talent to do it.
Coaching changes can assist in the decision-making process for draft-eligible underclassmen. Even though South Carolina's 2-8 season resulted in Will Muschamp getting fired, there are some good players leaving Columbia early. Jaycee Horn and Israel Mukuamu were the team's top defensive backs and linebacker Ernest Jones was the team's leading tackler in each of the past two seasons. Now, the Gamecocks will have to rebuild a defense that finished 12th in the SEC in points per game allowed.
Ho hum, just another year of Alabama saying goodbye to underclassmen who helped win a national title. Quarterback Mac Jones, receiver Jaylen Waddle and cornerback Patrick Surtain II are all first-round talents, and linebacker Dylan Moses is a stalwart. But perhaps no one helped their stock more this past season than defensive lineman Christian Barmore. The redshirt freshman had three TFLs and two sacks in the College Football Playoff. Yes, Alabama will likely reload at those positions, but here's what Alabama is losing: the nation's leading passer, the team's fastest wideout, one of the best-graded corners in the country and a disruptive force in the trenches. Good problems to have, I suppose.
The Hurricanes have quarterback D'Eriq King back for another season but lose three star underclassmen. Defensive ends Jaelan Phillips and Gregory Rousseau were the team's top two pass rushers, though Rousseau opted out this past year. Phillips led the team with 15.5 TFLs and Rousseau had 15.5 sacks in 2019. Also gone is star tight end Jordan Brevin, who was one of King's favorite targets with 576 receiving yards and seven touchdowns.
A year after losing nine underclassmen to the draft, LSU once again finds itself saying an early goodbye to key players. The team's top two wideouts -- Ja'Marr Chase and Terrace Marshall Jr. -- have declared with Chase opting out of the season before it began. Defensive lineman Tyler Shelvin also opted out before the start of the season. While the Tigers had a lot of time to adjust to life without Chase and Shelvin, that doesn't mean their losses aren't significant.
Pound for pound, BYU is one of the hardest-hit teams by underclassmen leaving early. Following an 11-1 season, quarterback Zach Wilson, offensive lineman Brady Christensen and receiver Dax Milne all declared. Wilson, of course, is projected to be a top-five pick. Christensen was an All-America tackle on a strong offensive line and could also go in the first round. Milne was Wilson's safety net, catching a team-best 70 passes for 1,188 yards and eight touchdowns in 2020.

Honorable mentions: Auburn, Louisville, North Carolina, Oklahoma