This isn't a positional ranking, but rather an overview of the depth and talent of the positions before we get into the prime section of draft season.
Quarterback - This quarterback class is better than last years by far; Deshaun Watson was probably the only QB picked last year who showed the type of ceiling he has in college while everyone else had their stock blown up. But in this class, we have the highest amount of hype for a QB since Tim Tebow in Sam Darnold, the original Sam Darnold in Josh Rosen, the more lethal version of Marcus Mariota in Lamar Jackson, and the natural-born leader, but more troublesome version of Drew Brees in Baker Mayfield. Now, those are not nailed down comparisons, but rather the style of play or reputation they all had in college. This class has some depth with players like Josh Allen, Mason Rudolph, and Luke Falk with plenty to offer behind those top 4. Overall, this QB class gets an A grade. It's hard not to with so much potential and proven talent.
Running Back - You'll hear this a lot as we get closer to the combine; this running back class is loaded. It took a pretty sizeable hit, however, when the second best back decided to go back to college for his senior year. That would be Bryce Love, who might have even snuck into the first round. Nevertheless, there's still so much talent in this class, and it starts with the obvious top back in Saquon Barkley. He's drawn comparisons to LaDainian Tomlinson with his running style and offensive versatility, and I'm buying that comp. Way too early to confirm it, but I don't see any reason why he can't be just as good of an offensive weapon. Behind him is muddy water for who's the next best back, but there are plenty of worthy candidates. If Love declared, it would've been him. Easily. But now we're to choose between angry runner Derrius Guice, shifty back Sony Michel, and do-it-all back Kerryon Johnson. I'm inclined to give this class an A+, but Love isn't there so this class gets a B+. I know this class is loaded, but realistically, there's only one back who is going to be the sole starter of a team. Everyone else is probably going to be mixed into a 2, 3 back system.
Wide Receiver - I don't look down on this receiving class, but it could be much better. This year boasts two great receivers, but behind them are one year wonders or underperforming players. The top two are Calvin Ridley and Courtland Sutton, both players who focus on actually catching the ball and not making the catch look good. That's what most of the future classes will suffer from, but these two are exceptional exceptions (see what I did there?). They have a chance to change a team's offense entirely. Behind them is a mix of slot receivers or red zone threats in Christian Kirk, Equanimeous St. Brown, and Auden Tate. Not to mention the breakout star in Andrew Miller, who has drawn comparisons to Stefon Diggs. This class gets a B-, but not because of lack of skill rather a lack of proof. All of these guys have a good skill set, but Ridley and Sutton are the only two who have the stats to back it up.
Tight End - There are never any "break out" classes for tight ends because it's a dying position. Last years class was supposed to be one for the ages, but only one tight end had a good year, and that was Evan Engram, who saw every receiver on the team go down to injury. This year, however, the tight ends entering the draft are going to be difference makers, but not on the stat sheet. These tight ends are good blockers and make the small catches needed to move the ball down the field. Hayden Hurst and Mark Andrews are the two top tight ends, one of which was part of the top offense in the nation. The other tight ends in the draft were key parts of top rushing attacks, such as Wisconsin's Troy Fumagalli and Stanford's Dalton Schultz. This class isn't flashy, but they are reliable and get the job done. This class gets a B, mainly because there's depth in this class.
Offensive Line - Last year saw a dip in the amount of premier offensive linemen available, but the year before had quite a bit of surprisingly good linemen. This year, it's supposed to be more of the same; good linemen, but mixed with some uncertainty. The thing that separates this linemen class from others is how much has changed in the rankings. The top linemen, Notre Dame's Quenton Nelson and Mike McGlinchey, have stayed atop the list throughout most of the year, but beyond that, players like Connor Williams, Braden Smith, Mitch Hyatt, and Chukwuma Okorafor have all seen dips in their stock while Isaiah Wynn, Frank Ragnow, Orlando Brown, and Will Hernandez have all seen their stock rise. There are also some other consistent linemen, like Billy Price and Bradley Bozeman, which is going to be a deciding factor on where they land. The class as a whole gets an A-, but that's boosted by the special talents of Nelson, McGlinchey, and Price. Beyond them is, as said before, uncertainty, but these three linemen are going to be guaranteed Pro Bowlers.