But keep in mind that Jones also got Alabama coaching

Jones is 3 inches taller, which automatically gives him an advantage as a pro prospect. I think they are probably about the same strength, as Jones is only 8 pounds heavier than Book.

But coming into college, Jones was ranked a 3 star (.8815) by 247 sports and Book was ranked a 3 star (.8681). Jones was the #29 QB recruit in his class, Book the #28 QB recruit in his. I'd give a slight edge to Jones for the higher number score and the fact that his QB class was a stronger class, but that is pretty comparable in terms of raw material.

done 4-5 years ago to rate individual players now? I'll never understand people who refer back to those rating as proof of "talent" or lack thereof for a given player.

100 five stars will be more talented as a group than 100 3 stars 5 years later, but the rating (to 4 decimal points!) doesnt say anything about the individual now that isnt much more readily observed on the field.

It indicates that they were comparably thought of coming out of high school. (If you have a better/more accurate system for estimating the approximate ratings of two players at the same position, I'd love to hear it.)

Then Book got 5 years of coaching from Brian Kelly and company
Jones got 4 years of coaching from Nick Saban and company

I think that has almost everything to do with their respective performances on the field this year, who is the more complete QB, and who is the better NFL prospect.

Jones is clearly better, will be drafted higher, and will have a better pro career. Even the Bears or Lions wouldn’t draft Book over Jones.

I started by posting that I thought Jones and Book were of similar raw athletic ability and talent and that I thought Jones' superior performance on the field was due to playing in a better system and receiving better coaching

You responded that Book never would have started over Jones

I responded that you may well be right, but that the two quarterbacks were rated similarly coming into college, but that one received coaching from Alabama coaches for four years.

You responded that you don't know what their rankings have to do with anything.

Their rankings (which are imperfect, but as good of an approximation of original raw talent as we have) have everything to do with my point. It's not like Mac Jones was looked at as some "can't miss" prospect coming out of high school and Ian Book was some walk-on who had never played the game before; they were fairly comparably thought of coming in. Yet Jones ended up in the top three of the Heisman voting. I think that speaks volumes about the level of coaching he received and the system he played in at Alabama.

Jones was a better player then and is a much better player now. The recruiting services got it wrong if they rated the two of them almost equally. That's hardly a surprise though.

Also, there are literally thousands of three star recruits, and that ranking does not necessarily mean they are all relatively equal. Jones' size and arm strength have always been and will always be much better than Book.