Wondering how the Yard feels about that question. I was doing some research and came across the year after our first national Championship 1999-00. We were pre season #1 but we finished 25-10, 10-6 , Big East and lost in the second round. El-Amin, Mouring, Freeman, Voshul, Edmond Saunders who was a stud out of Waterbury and the highly over rated Ajou Deng ( wish we got his brother). Maybe it was a stretch to have that high of a pre season ranking but I just remember being frustrated with that team. I was trying to figure out at least for me the most disappointing seasons. I think it is between this year and that year.
All of the usual suspects have been identified by others, so I'm going to change the terms. The OP provides the perfect springboard.
My theme is 5 that ended in sadness and disappointment due to a key late-season injury.
In 1996, Ricky Moore dislocated his shoulder in the 1st Round game against #16-seed Colgate. 32-2, #1-seed UConn lost to #5-seed Mississippi State in the Sweet 16 game.
In 2000, Khalid El-Amin's game 1 high ankle sprain resulted in "the limp" 13 minutes into game 2that sealed #5-seed UConn's fate against #4-seed Tennessee. No Sweet 16 after the National Championship season. This was the team that
@Huskie62 used to open the thread
In 2008, AJ Price tore his ACL 9 minutes into the first round game that #4-seed UConn lost to #13-seed San Diego..
In 2009, Jerome Dyson's torn meniscus when eventual #1-seed UConn was 23-1, was prelude to UConn's only loss in Final Four competition, being defeated in Detroit by #2-seed Michigan State in the Semi-Finals.
In 2021, RJ Cole fell hard to the floor and banged his head in the Big East Semi-Finals, as eventual #7-seed UConn lost to Creighton. Even though RJ returned for the NCAA game against #10-seed Maryland, he was not fully effective, and UConn suffered another First-round loss to a lower seed.