2016 was when our secondary was so poorly coached and there were so many injuries, that we had no choice but to use the best available guy at the position. Given the circumstances, he did about as well as any rookie could have done.
2017 was when Jalen Elliot started making some decent strides, and essentially grabbed the position, having separated from the others.
There was no way that Studstill would have taken either safety position from either Elliot or Gilman in 2018. I don't blame him for transferring, especially given that we have some pretty strong safety talent coming up in the ranks. Derrik Allen comes to mind, and with Houston Griffith moving over to corner, it's pretty much a given that we're set at the safety position.
Best of luck to Mr. Studstill. He represented ND well, and I hope he kicks butt wherever he goes.