It is the same as asking a high school team to play college seniors.
Alabama is dominant in the realm of college football. But there are strict restrictions on how the teams get their players, when they can recruit ect. There are even strict restrictions on when and how often they can practice.
You would be hard pressed to find a more dedicated Crimson Tide fan than me. But any pro team has a far better roster of athletes.
There are over 1 million kids playing high school football. Only 3-4% of those will play college football. Mostly they are the cream of the crop. But that is still 30k to 40k kids playing college football.
In the NFL there are 1,696 players. Each of them was probably a starter in college. While each individual might not beat the stars on Alabama's roster, they are not far off. And most will be superior to most of Alabama's players. Plus, they will have had more years of training, experience and coaching under their belt.
Think about the difference between most college freshmen players and college senior players. The NFL players will have that much more.
Alabama has a powerhouse this year. And I am a die-hard Crimson Tide fan. But no, they could not beat the Browns.