No matter how stacked a college football team is at six of the seven major position groups—quarterbacks, running backs, receivers, offensive linemen, defensive linemen and defensive backs—the presence of just one Achilles' heel is enough to undo an otherwise promising season.
For proof of this theory, look no further than its converse: That balance among all seven position groups is the key to becoming a champion. Care to find any discernible holes on the 2013 Florida State Seminoles or the 2012 Alabama Crimson Tide?
One weak unit is enough to keep a team out of the College Football Playoff, and in 2014, the Playoff's first year, there will be no shortage of semi-flawed teams working to mask their biggest deficiency.
Whether said unit returns a bunch of underperforming pieces or loses most of its starters from 2013—or some combination of the two—there are reasons to believe it can hold the team back this year.
Whether it will is a different story, a narrative that depends on coaching and commitment from the players. But in all of the cases that follow, the unit has at least a couple of looming questions that could keep an otherwise championship-caliber team out of the CFP.
Chime in below, and let me know where you disagree.