Purdue coach Ryan Walters hears the noise from outside the Kozuch Football Performance Complex. He knows about the grumblings, the doubters following two painful losses. “During the season, I don’t really open Twitter or read articles unless it’s for recruiting purposes,” he said. “I try to encourage our guys to do the same. Obviously, I’ve got a couple friends that think it’s funny to send me tweets to rib me a little bit.” Given Purdue is coming off an historic 66-7 loss to Notre Dame and a numbing 38-21 setback at Oregon State, Walters’ buddies have had a lot to rib him about. But the secon…