I love/hate these discussions. Hate because there's an obvious answer. Love because it's one of my favorite things to unpack anyway.
Ohio State might have 25 guys on the roster who will one day play in an NFL game. Some of them are freshmen and sophomores right now, and aren't ready for prime time just yet; some of them are stud juniors who are going to get into an NFL camp, maybe play a few preseason games, etc. If they're one of the absolute most loaded college teams ever, they might have 10 guys who are going to become NFL starters for at least one full season. The Cleveland Browns have 53 guys on the roster who are all playing in the NFL right now. It's not out of the realm of possibility that OSU could win one fluky game against the worst team in the NFL, but the odds are very long against it...
Think of it this way. JT Barrett is playing great right now. Maybe even one of the best college QB's in the country. If he were in the NFL right now, where does he rank among starting QB's? Probably like 27th or 28th, right?
Now project that across every position. OSU or Alabama, in a really good year, might have two or three guys who are actually ready to walk straight onto an NFL roster and play tomorrow. Derrick Henry, who won the freaking Heisman Trophy for Alabama last year, is mostly riding the bench as the #2 running back behind DeMarco Murray on a 3-3 team. Henry might be the 25th-best running back in the League, if we're being on the generous side. And he was the King Kong running back behind Alabama's dominant play last year.
The only reason the Browns (or Jaguars, or whoever else is awful in a given year) look so inept is because they're playing against other teams that are all composed of even better NFL players. Even the greatest college teams ever are typically starting at least a handful of guys that will never make it into the League.
One of my favorite test cases for this is 2002 Miami, one of the absolute most talented college teams ever. The starting 22 has Willis McGahee, Andre Johnson, Kellen Winslow, Jonathan Vilma, Antrel Rolle, Sean Taylor...I mean, this is about as loaded as a college team gets, right? But then again...there are still a bunch of guys starting who didn't even sniff the League or barely played. Ken Dorsey started 13 NFL games, went 2-11 and threw twice as many INT's as TD passes. WillisMcGahee and Frank Gore in the backfield is pretty damn solid, but Andre Johnson is the only WR who even played in the NFL. Only two of the five starting offensive linemen played in the NFL (Romberg and Carey; and Romberg started a total of 18 NFL games in five seasons, hardly an every-down guy). The defense has Vilma, Rolle, and Taylor (all of whom became or would have become solid NFL players) plus some fringe NFL guys that hung around for a couple seasons like William Joseph and Jerome McDougle, but again, half the starters never made it past a training camp.
We can go through this exercise with any of the dominant college teams in recent memory. Vince Young's Texas teams, the USC dynasty, etc. Many of these teams which looked absolutely unstoppable in college are going to have the same profile: a handful of guys who did go on to become absolute stars in the League, another handful that maybe got into a training camp or hung around as a fringe player, and at least a dozen starters who never played a down of professional football.
The Browns, inept and clumsy though they look, are 100 percent comprised of guys that have made it into the NFL. Duke Johnson ran for 1,652 yards as a junior at Miami. Corey Coleman had 1,363 receiving yards last year for Baylor. Gary Barnidge was an all-league tight end at Louisville. Terrelle Pryor was as talented a pure athlete as Ohio State ever had at QB. The team is literally full of guys who were the best player or one of the best players on their respective college teams.