By Tony Pauline, Special to SI.com, TFYDraft.com

The college season kicks off this weekend, and with it another year of NFL scouting begins in earnest. Tight end, tackle and center offer the greatest depth on offense, with the skill positions lacking top prospects from the senior class. No senior quarterback, in fact, grades out as a first-round pick. But as you'll see in this early rundown of the top offensive prospects for April's draft, that position could be helped immensely by an infusion of underclassmen talent. (Defensive prospects coming on Wednesday.)

Quarterbacks

Matt Stafford/Georgia (Underclassman): The Bulldogs' gunslinger needs some polish to his game but will be a nice fit during the second half of round one if he declares for the draft.

Cullen Harper/Clemson: National Scouting and Blesto, the league's two scouting services, grade Harper as the number one senior quarterback. He has the arm strength to play at the next level, though his accuracy is suspect.

Tim Tebow/Florida (U): College football's premier quarterback hopes to repeat his Heisman Trophy performance from a year ago. His physical skills are unquestioned. However, his fundamentals coupled with the freelance style of play he is accustomed to on the college level has some NFL scouts concerned.

Hunter Cantwell/Louisville: As a backup to Brian Brohm, Cantwell has started just four games at Louisville. But he has the size and arm strength teams want in a No. 1 quarterback. A big senior season could stamp him as a first rounder in April.

Tom Brandstarter/Fresno State: He's a smart passer with an accurate arm. He looks best suited to play in a west coast offense at the next level, where his intelligence would be extremely valuable.

Sleeper

Stephen McGee/Texas A&M: He was out of place running the Aggies option offense the past three seasons. Mike Sherman's pro-style passing game should suit McGee perfectly.

Overrated

Curtis Painter/Purdue: One of college football's most prolific passers the past two seasons, Painter's poor mechanics, decision-making and inability to come through in the clutch does not translate well to the next level.

Running Backs

Like quarterback, the top prospects at running back can be found in the ranks of the underclassmen.

Chris Wells/Ohio State (U): He's a complete back and a potential franchise player for the next level. He is a dominant interior ball carrier who shows great skill running in the open field. He could end up as the highest rated player and the draft's first selection if he opts in.

Knowshon Moreno/Georgia (U): The sophomore possesses a great combination of size, physical skill and running instinct. He's a north/south runner who would fit most offensive systems.

James Davis/Clemson: He made the right choice earlier this year by withdrawing his application for the 2008 draft. The tough, straight-line runner is at his best running between the tackles.