Tom Thibodeau tried to give Nikola Mirotic minutes as a SF last year. The results were very poor.
This is why many cringed when Zach Lowe broke the news last week that Fred Hoiberg would be trying Mirotic at SF again.
So far, the results have been pretty much what you would expect. Here is the breakdown of the +/- that Niko has provided over the past 4 games as a SF vs. a PF
Summary of Niko's stats over past 4 games:
Bulls w/ Niko as SF: -13
Bulls w/ Niko as PF: +16
Not only are Niko's individual stats slightly down over the past 4 games, but the team isn't playing better with him at SF either.