A guy lines up wrong, maybe off his mark by only a yard. Then another guy misses a tackle.
What have you got?
"Bad news,'' Justin Wilcox said Wednesday.
Tennessee's defensive coordinator knows bad news when he sees it and looking down from his perch in the press box, he's seen it several times already in 2011.
Montana: 80-yard touchdown pass over a freshman defensive back.
Cincinnati: 65-yard touchdown run.
Florida: 3-yard pass turns into an 83-yard touchdown.
Every defense is going to get beat from time to time. Did you see the Miami Dolphins give up a 99-yard TD pass to the Patriots on opening day?
But the goal is to prevent those bad plays from turning into "catastrophic" plays. Wilcox's terminology, not mine.
Of course, it's a challenge. The turnover in Tennessee's defensive personnel from last year to this year has been significant to say the least.
The turnover spilled into August when free safety Janzen Jackson, arguably the defense's best player, was dismissed.
"We're doing some good things,'' head coach Derek Dooley said, "but we're giving up just these enormous plays that are killing us.''
The good things? Dooley said of 217 defensive snaps this season, 208 have yielded an average of 3.3 yards per play.
Ah, the killers? The other nine have averaged 46.4 yards per play.
The goal is to give up zero plays of 25 yards or more. Mission accomplished — except for three plays in each of the Vols' three games.
Montana had the 80-yard TD pass, a 32-yard completion and a 27-yard run.
Cincinnati popped a 65-yard TD run on the opening possession, had a 27-yard run and a 46-yard pass.
Florida had a 28-yard run, a 28-yard pass and then Chris Rainey's 83-yard score, the longest pass reception by a running back in Florida history.
UT has been burned for the longest two pass completions in the young SEC season. There have been two runs from scrimmage allowed longer than Cincinnati's, both by woeful Ole Miss.
In reality, UT should be content if it could just eliminate the three catastrophe plays. If a 28-yard run is the best Florida can do, you take that and get on the plane.
"Usually what happens,'' Wilcox said, "is there's a bust by at least one person, usually accompanied by a missed tackle.
"You can't have that. It can't happen. You're going to have bad plays, but you've got to get the guy on the ground, line up again first-and-10 and make them drive the ball.''
Like really good defenses do.
The longest play Alabama has allowed in three games is 27 yards. The longest LSU has yielded is 25 yards.
Tennessee's defense, on the other hand, is very much a work in progress. Most everyone is in a role or position different from last season. Four true freshmen see significant action, two at linebacker and two in the secondary.
"There are no do-overs,'' Wilcox said. "You don't get 'em back. They've got to understand that.''
Dooley has talked of players acquiring battle scars as they mature.
The next step is keeping those scars off the scoreboard.