Look at McDonald's eligibility. He's unbalanced (a senior in indoor track, redshirt junior in outdoor). He's obviously not running in a Wisconsin uniform for indoor track this year, which balances him out, and gives him one more year in each three seasons.
Couple this with getting to (hopefully) run in the Commonwealth Games in his home country, and this seems to make sense. There are plenty of things to be angry about with the Badgers this year (particularly with no appearances from Hacker or Snider yet this year), but I'm not sure this is one of them.