The fundamental problem is that anything which elevates the Knoxville campus is seen by many as being at the expense of the rest of the system. Petersen's a politician, not an academician; he's pursued a least common denominator strategy of spreading resources around to keep people in Chattanooga and Martin happy. If you want to have a true top-level flagship campus, then you have to treat (and fund) it as such, and Petersen has been unwilling to do so because it ruffle feathers in the rest of the system. (You can even see evidence of this approach when you're watching a UT football game on TV. The UT ads these days don't mention Knoxville in particular, referring instead to "the statewide campus of the University of Tennessee.")
Anyway, things finally came to a head last year when Petersen ousted Loren Crabtree, chancellor of the Knoxville campus and the best administrator UTK has had since I walked on campus as a freshman 20 years ago. It looked as though Crabtree was finally fulfilling some of the long-stated aims of making UTK into a top-level state school, but that put him into conflict with Petersen's priorities for the rest of the system. Exeunt both Crabtree and Tennessee's only real shot at having a high-level public university.