When analyzing NFL rosters, it's important to remember that it's all relative. It's easy to say a team is in "good shape" or "loaded" at a particular position, but the fact is, each unit is only as good as it is relative to the league's other 31 teams.
That might seem like common sense, but you'd be surprised what you can learn and how your opinions are adjusted by actually sitting down and objectively grading and/or ranking each positional unit of all 32 teams. This is a project I've done (and kept updated) each of the past several offseasons, which has led to many interesting revelations, including the likely breakouts of teams such as the 2016 Raiders, 2017 Chargers, 2017 Jaguars, 2017 Eagles, 2018 Browns and 2020 Buccaneers.
Here are position-by-position unit rankings for all 32 teams covering the 10 key offensive and defensive positions. At the end, an overall ranking is shown, which is a weighted consensus based on positional importance. For example, being elite at quarterback is obviously more important than being elite at running back. Also included for each position is a brief outlook on the best and shakiest units, as well as one intriguing unit worth keeping a close eye on. Note that these are 2021 rankings, not long-term outlooks.
Best: Kansas City Chiefs
It's cool if I simply update what I wrote here last preseason, right? League MVP? Check. Super Bowl MVP? Check. Multiple Super Bowl starts? Check. Highest paid player in league history? Check. Rating of 99 in Madden? Check. You get it. In only three full NFL seasons, Patrick Mahomes has a résumé few quarterbacks manage for a career. He's the league's best QB and most valuable player.