He can see it on film, and he can hear it in the voices of his players. It's enough to make Wilson optimistic that a flurry of offseason changes may finally give the Hoosiers the kind of defense that could get them to a bowl game.
''Going through our first walk through, they are significantly louder than I've ever heard a defense since I've been here,'' Wilson said Monday, his fourth media day at Indiana. ''Communication is what you need. You need to get the call and get lined up. ... When you're unsure as a player, you're quiet.''
But before speaking up, the Hoosiers needed a major shake-up.
They finished last in the Big Ten league in scoring defense and yards allowed per game each of the past three years, and were getting progressively worse in the yardage department. Though, the Hoosiers allowed a Big Ten-worst 38.8 points and 527.9 yards last season, that wasn't even the worst part. Indiana shattered Northwestern's previous league record for most yards allowed in conference play with an astounding 560.2. The Wildcats allowed 524.7 during a winless 1981 season.
Despite all of those problems, Indiana still managed to go from 1-11 to 4-8 to 5-7 over Wilson's first three seasons.
Wilson began his overhaul in January by firing defensive coordinator Doug Mallory, the son of Indiana's beloved former head coach Bill Mallory, and defensive line coach Jon Fabris.
Ten days later, he hired Brian Knorr, the former Ohio head coach and Wake Forest defensive coordinator, as Mallory's replacement. Knorr will work with defensive ends and outside linebackers this season.
Knorr quickly converted Indiana's 4-3 defense into a 3-4, moved defensive lineman Nick Mangieri to outside linebacker and started devising new ways to pressure opposing quarterbacks. Players embraced the changes almost immediately.
''I love the blitz packages,'' linebacker Flo Hardin said. ''I asked (quarterback) Nate (Sudfeld) in the spring about them, and he said he could never tell where the guys were going to come from.''
While Knorr has mastered the art of taking seemingly undersized players and turning them into all-league players, he starts with a stronger hand at Indiana.
The Hoosiers opened practice Monday with 286-pound Bobby Richardson, 307-pound Adarius Rayner and 325-pound Ralph Green III listed as the defensive line starters, and Mangieri, 260 pounds, and 240-pound David Cooper as the No. 1 outside linebackers.
Knorr also has 14 of his top 15 tacklers back from last season, including nine starters and cornerback Tim Bennett, who led the nation with 20 pass breakups in 2013.
''We looked at how many points we gave up and how many turnovers we created (17) versus other fast, up-tempo teams and we're going to be on the field a little more,'' Knorr said. ''We embrace that as an opportunity. But takeaways are something that's going to be very important to us because if we get those, that's two or three more (offensive) possessions per game.''
The philosophical changes have been noticeable as the Hoosiers went through spring practice and summer workouts.
Hardin said he was eager to show off Indiana's new physical, aggressive style, and Bennett smiled when asked about the emphasis on turnovers.
''It's controlled chaos out there,'' Bennett said. ''If the quarterback doesn't know what's going on, you can take advantage of that split second and step in front of a receiver and take it away.''
But the most promising sign of a turnaround might are the subtleties Wilson has noticed in practice, like the noise level.
''I saw it every day. I saw a team that had a vibe and a bounce. I think as much as anything, not schematics or schemes or anything in coaching, I just think it's where the kids are,'' Wilson said. ''We've just recruited harder and tried to develop. It's still not close to where it ought to be. I didn't say it's what we want. We have a long way to go to what we needed to get to as a team.''