The MSU 12-13 team had one freshman in its top 5 in points or minutes and Appling, Payne, and Nix were 3 of the top 4 scorers. I'm fairly confident that if only one MSU freshman plays in the top 5 minutes next year, or if three of their leading scorers are Schilling, Harris, and McQuaid, it won't be a good thing.
This is a huge blow for MSU, significantly lowers their ceiling -- I've seen MSU up close, and the difference between what Davis could have brought and what Goins (or Schilling) could bring is enormous. And the downside variance is much greater.
Izzo is a very good coach, they'll still have plenty of talent, and they may have a terrific season, but it'll rely much more on freshmen than Izzo generally does, and the chances of a mediocre season are much higher.