I do not see the love for Jack. He's been here four years, admittedly injured for most of his second year playing, and has not really shown anything but average offensive skills, below average rebounding skills and poor defensive skills.
Jack is 6'11" and averaged 4.6 RPG during his five games. C Mac averaged 4.0 over the season. Wouldn't the size differential be most significantly displayed in rebounding? Stats are not everything but they are important metrics of success and skill. Assuming Jack gets more inside shots, because he as a six inch height differential with C Mac, his production is not significantly more efficient JN 36.4% / C Mac 34.4%. Another insignificant difference at doing something that is helped by size. JN inferior in almost every other metric.
Even the intangibles skew toward C Mac. The Hawks will not face a lot of big guys that can effectively chase Connor around the floor when Iowa's got the ball. C Mac will struggle with defense when he gets isolated down low against a much taller opponent but that guy still has to hang on the other end as well. Barring injuries or big foul trouble, Connor will always be surrounded by good to great scorers so that big man chasing him is probably not going to be in a position the help on the other four players. The more up tempo and fluid the game the less significant size poses for Connor.
C Mac is stronger and more physical and can play some emergency post defense against bigger players. Jack is 6'11' but plays like he's 6'5". It is no coincidence that the team improved its play after the "Jack as a forward" experiment ended. I'm never going to write off a player before their career is over-having been so wrong going into Eric May's senior season-but at this point Jack Nunge has not demonstrated an ability to be anything but a reserve center, playing behind a 1st Team AA center. That could change but at this point, based on just eyeball, I think both Murrays are better options.