1) Pitino hasn't "proven" he can coach. That's not the right word to use anyway. One doesn't "prove" he can coach in the same way that an investigator "proves" or "disproves" that someone committed a crime or a scientist "proves" or "disproves" a theory. Coaches have to "demonstrate" consistently that they can coach successfully. By successfully, the most important factor is how well they perform in relation to their peers (and, to be fair, there can be different levels of peers even within the same conference - no one ever expects us to do as well in football as Ohio State). The evaluation of coaching is an ongoing process. That's why most coaches eventually get fired. Having one really good year doesn't "prove" anything.
2) The NIT run in his first year was a nice memory. But, we should mention the following:
a) He was handed a veteran team. Admittedly, he improved that team by getting Walker in playing shape and recruiting DeAndre Mathieu.
b) They had a pretty easy run to the NIT final four getting to play High Point, St. Mary's, and Southern Mississippi all at home. They did win both games in Madison Square Garden but one was by 3 points in overtime and the other was by two points.
I did very much enjoy that run (even went to the St. Mary's game) but their NIT championship wasn't nearly as impressive as Penn State's, who faced tougher competition and had only one home game, this season. In some ways, the feat of Tubby's young and injury depleted team of two years earlier that went to the final game while playing all of their tournament games on the road was more impressive.