The class of 1962 was pretty disappointing. Norm Grow came in regarded as the best high school player ever to come out of Minnesota, but was never able to contribute or get any minutes to speak of. Ray Cronk from Bemidji as also highly regarded, and he turned out to be a solid player. But after 2 good seasons he was declared academically ineligible for his junior year of 1960-61. He did return for his senior year but was not as effective as he had been.
The previous class (class of 1957 out of high school, 1961 out of college) was similar. Paul Lehman came out of DeLaSalle and became a starter, but he blew out his knee and was never the same. Jerry Butler had led Mpls. Roosevelt to consecutive state titles, but ended up not being good enough to contribute.
Then there's the class of 1963/1967. Lou Hudson broke his wrist and was notable impaired his senior year, and Don Yates was academically ineligible for his senior year. Still this group finished 2nd in the Big 10 as juniors so it's probably not fair to say they were a disappointment, other than that expectations were very very high.
How about the class of 1974/1978. Olberding played 1 year. Thompson spent much of his career on probation. Landsberger left after 1 year. Osborne Lockhart was in that group as well.
And the class of 1978/82 included Trent Tucker and Darryl Mitchell, but also Leo Rautins, who transferred to Syracuse, Mark Hall, who became ineligible, and Brian Pederson, who retired due to a bad back. Of course Tucker and Mitchell won the Big 10 title in '82 with Randy Breuer so I guess you can't say they turned out badly.
