Badgers head coach Bret Bielema announced after Saturday's practice that Casillas, sophomore wide receiver Maurice Moore and redshirt freshman quarterback James Stallons will not travel to Orlando, Fla., when the team departs Monday morning. Both Casillas and Moore recently underwent surgeries.
Bielema said the team had at least one academically ineligible player but declined to say it was Stallons, citing privacy issues. Wisconsin could have other academically ineligible players but might not know until the day before the bowl, when semester grades are due.
Casillas, a three-year starter who twice earned honorable mention All-Big Ten honors, ranks third on the team in tackles (62) with six tackles for loss and an interception. He sustained a knee injury in preseason camp and missed the first two games before starting the final 10.
Bielema told reporters Casillas experienced "some new pain or new discomfort" during bowl practices and underwent surgery last week. Casillas finishes his college career with 251 tackles.
Junior middle linebacker Jaevery McFadden will move over to Casillas' spot on the weak side, and sophomore Culmer St. Jean is expected to start in the middle.
Moore appeared in six games, making five receptions for 61 yards.
Stallons, who is fourth on the depth chart, did not play this season.
Adam Rittenberg covers the Big Ten for ESPN.com. He can be reached at firstname.lastname@example.org