That's the way it is every year with TEs. There's the elite guys like Jimmy G, Gronk, and Orange Julius, then the solid-but-uninspiring guys like Olsen and Gates. Vernon Davis and Witten used to be the solid-but-uninspiring guys, but their roles have changed this year to more blocking, so that may affect perceptions that the position is having a down year overall. Also Jordan Cameron (when healthy) is severely underutilized.
Most TEs (even Julius) seem extremely inconsistent, which they are: a lot of them are touchdown-dependent fantasy options.