Ranking 2021 NFL free agents: George Kittle, Joey Bosa among top 25 players who could hit the market

Eight days into the NFL's 2020 free-agent market, there is really only one thing left to do: start planning for next year.

What follows is a two-tiered look at the potential 2021 class one year out. We've separated the 15 players who received either the franchise or transition tag this spring. Some probably will sign long-term deals over the next few months, but for now, all of them remain eligible for free agency next year.

The 2021 class could be dominated by the high number of running backs from the 2017 draft class. We know that teams generally don't chase tailbacks on the open market, unless they bring substantial value in the passing game, and we've tried to skew the rankings accordingly. There is also a surprisingly large pool of left tackles, one that is likely to dry up between now and next March.

Here are the top 25 players set to hit the market in 2021, with age and position taken heavily into consideration.

Note: This list does not include first-round picks from the 2017 draft, including quarterbacks Patrick Mahomes and Deshaun Watson, whose teams probably will pick up their fifth-year options for 2021.

1. George Kittle, TE

2020 team: San Francisco 49ers | Age entering 2021 season: 27

Arguably the best tight end in the NFL -- and one of the league's best overall players -- would shatter precedent if he ever got on the open market. Given the relative efficiency of the tight end franchise tag number, it's hard to imagine the 49ers ever letting it get to that point.

2. Joey Bosa, Edge

2020 team: Los Angeles Chargers | Age entering 2021 season: 26

After an injury-shortened 2018 season, Bosa roared back in 2019 to play in all 16 games and record his third double-digit sack season (11.5) in four years. Even after missing 13 games in four seasons, Bosa leads the 2016 draft class in career sacks (40).

3. Ronnie Stanley, OT

2020 team: Baltimore Ravens | Age entering 2021 season: 27

It's difficult to imagine the Ravens allowing Stanley to move on. Left tackle is one of the most difficult positions to replace, and in 2019, Stanley earned All-Pro and Pro Bowl honors.