I've seen several theories on here about what happened. I think some have merit. Here's mine.
There were times this year, such as the first Mizzou game, that the Vols looked absolutely fantastic. We had 5 outstanding guards, 2 of them possible lottery picks. But the only reliable inside scoring threat was Fulky. When he was healthy, we were really good, but for much of the season he wasn't. Starting in early January, his energy was clearly lacking, for whatever reason. He wasn't the same as he was last year, or even in December. When his inside scoring threat was gone, our outside game suffered as well. He seemed to be getting it back in late February, especially the 2 Florida games. That's when we looked like a team that could make a deep run. Then it was gone with one elbow swing.
It was Florida that knocked us out of both the SEC and NCAA tournaments.