Narrowing down the best underclassmen (non-draft-eligible players) in college football into a single top 25 ranking wasn't easy. Not only are there a lot of worthy candidates, but in watching these guys on tape, you could really notice a difference between the true freshmen and the second-year players (redshirt freshmen and true sophomores) -- there was a significant gap in terms of technique, awareness and physicality.

In ordering the top 25, we took the following factors into account:

-- While players in their second seasons who were more polished and consistent were rewarded for it, we tried to also balance out a first-year player's overall talent and potential when comparing the two against each other. This is a ranking of college ability, not pro potential (although there are plenty of guys on this list with the chance to make the NFL one day), but upside still factored into how we ranked players.

-- Injuries had an impact on the rankings, both in terms of durability concerns and the fact that being limited by injury or missing games cut into certain players' productivity.

-- When we were stuck on how to rank one player in comparison to another, we asked ourselves the following question: If you could have two or three more seasons with any of these players at the college level, who would you recruit to play for your team? Each player's potential and durability factored into answering that question.

With those factors in mind, here is our ranking of the top 25 underclassmen in college football for 2013:

Redshirt freshman | 6-foot-4, 228 pounds

Winston has uncommon poise for a first-year starting quarterback, which is reflected both in his decision-making and pocket presence. He has shown the ability to compartmentalize his off-the-field issues this season and maintain focus in his preparation and in games.

As a passer, Winston flashes excellent ball placement on difficult intermediate throws and throws a catchable ball. He does a good job of leading receivers and is very accurate when rolling to his right (he isn't as consistent when rolling left), although he does have a tendency to miss within the strike zone on passes over the middle.

Winston has very good velocity on his fastball and can squeeze passes into tight windows, getting good zip on his passes even when defenders are hanging all over him. He has an elongated delivery -- it isn't surprising he's a baseball player -- but his release is still quicker than most QBs who have his windmill style.

Going forward he'll need to prove he can lead his team from behind and deliver in "clutch" situations (he has yet to trail during the second half of a game), guard against overconfidence and improve his ball security (he's taken more risks during the second half of the season), but given how well he grades out on tape, it's no surprise he's the clear-cut front-runner to win the Heisman Trophy.

True freshman | 5-11, 192 pounds