While I certainly don't agree with the original silly premise that Barnes develops no one offensively, Knecht isn't a great example. He was pretty much a finished product, offensively, when he arrived on campus.
Kevin Punter, Jordan Bone, Admiral Schofield, Robert Hubbs, Grant Williams, Yves Pons, John Fulkerson, Zakai Zeigler, Jonas Aidoo among others are better examples of guys who spent multiple years at Tennessee and developed their offensive games across their time in a Tennessee uniform. None of those guys walked on campus as elite offensive players. OP would have you believe they either did, or that they simply defied Barnes's offensive regression plan.