Nolan Winter was listed as day-to-day after injuring his ankle against Maryland. This is the best-case scenario, but there's no way he's going to be 100% by Purdue. The injury looked too bad; he needed help off the court, he never came back, and the language after the game wasn't fantastic. "We may have dodged the worst-case scenario," from Greg Gard and "Nolan will play with one leg," from Blackwell.
Sure, there was optimism, but it did appear initially that there was a major need for recovery time. Which leaves a very obvious choice for Greg Gard regarding Nolan Winter versus Purdue. He needs to rest him unless he's 100% (which he won't be). There's no reason to risk making things worse and torpedoing the postseason. Give him another day of rest and recovery.
The Purdue game doesn't hold enough weight to cost a bigger injury to Nolan Winter
Sure, losing to Purdue is lame, and that's more likely without Winter, but the NCAA Tournament is more important. A fully healthy Winter is the only way the Badgers can make a run in March Madness.
Also, the Purdue game is not that important for either the Big Ten standings or the NCAA Tournament seeding. Most bracketologists are working on seeding Wisconsin with an assumed loss to Purdue somewhere around a 6 or 7 seed. The Badgers are almost assuredly stuck in the double-bye category of the Big Ten Tournament. There's a 1% chance Wisconsin can get the 4-seed. It would take Maryland beating Illinois and Wisconsin beating Purdue.
Thus, the game isn't worth it in comparison to getting Nolan Winter back for the postseason. Gard has to let him sit and rest his ankle for another day. Give him more time on the treatment plan. Of course, Winter will push to play because he's a fighter and he doesn't want to miss any games, but he needs to sit. Maybe, Garlock, Rapp, and Bielauskas will find that spark without him and shock Purdue anyway.