For the first time since late September, Notre Dame has experienced the pain of a loss.
The Irish were upset, 28-21, by Pittsburgh at Heinz Field Saturday evening. The Irish were doomed by three costly turnovers and inconsistent play on both sides of the ball, while the Panthers took advantage of nearly every Irish miscue.
Thus, much was left to be learned about the Irish.
Following are the 10 most significant lessons to be taken away.
After two respectable performances against Air Force and Navy, Tommy Rees had, perhaps, his worst outing of the 2013 season against Pittsburgh.
The Lake Forest, Ill., native threw two costly interceptions in the second half, after beginning the final 30 minutes of play with a hot hand. Unfortunately for Notre Dame, Rees' performance was reminiscent of his dreadful 2011 season, when the 6-foot-2, 215-pound quarterback was responsible for 19 of the Irish's 29 total turnovers.
One week after recording the best performance of his young career, Tarean Folston was a no-show against Pittsburgh.
The freshman recorded just 13 yards on four carries after rushing for a career-high 140 yards on 18 carries last week against Air Force. It goes to show the Irish running back position will continue to be by committee, and there is no such thing as a No. 1 running back within the offense.
Notre Dame's defensive line will be a liability without Stephon Tuitt.
The 6-foot-6, 322-pound defensive end was ejected early in the first half for a questionable targeting call, and the Irish defense simply wasn't the same without him. The Panthers began to run the ball at will, and momentum swung heavily in Pittsburgh's direction.
College football's targeting rule is in need of review.
While the rule itself is intended to protect players, the enforcement is questionable, at best. Tuitt did lower his shoulder against Pittsburgh quarterback Tom Savage, but malicious intent was nonexistent. His loss was a massive one for the Irish defense—and an unnecessary one at that.
Chris Watt didn't show any signs of being slowed from a PCL strain. The left guard was a consistent presence along the Irish offensive line for four quarters, a welcome sigh of relief for a team that has been racked with negative injury news during the past few weeks.
It seems once a year, Notre Dame loses to at least one team it has no business losing to. This season, that game was at Pittsburgh.
The Panthers entered the contest at 4-4, having lost to Georgia Tech and Navy in consecutive weeks. But the Irish played to the level of their competition, which was due in part to two costly Tommy Rees interceptions. Thus, the streak of annual fluke losses continues for the Irish.
With the loss to Pittsburgh, the Irish's BCS hopes were terminated.
Entering their matchup with the Panthers, the Irish were in a position of having to win out to qualify for a BCS game, and with a loss to the Panthers, that condition is no longer relevant. Thus, the Irish will be relegated to a lower-tier bowl game, such as the Little Caesar's Pizza Bowl.
TJ Jones continued to prove he is a legitimate No. 1 receiver after his performance against Pittsburgh. The senior hauled in six receptions for 149 yards, which included an 80-yard touchdown strike from Rees.
With such performances becoming the norm, Jones' draft stock improves on a weekly basis.
While no Irish running back had an impressive individual performance, the group itself combined to rush for 133 yards on 25 carries, good for an average of 5.3 yards per carry.
It won't satisfy the casual fan, but it's a group effort worthy of recognition.
While it didn't feel like it, the Irish defense limited Pittsburgh to just 2.8 yards per carry.
That's an amazing figure given the depleted nature of Notre Dame's defensive line, which was without defensive end Stephon Tuitt for three quarters. Given the rampant number of injuries among the front seven, it was a heroic effort that was seemingly the only bright spot in an otherwise gloomy outing.