Defense has often seemed to be nothing more than a rumor when it comes to Indiana, as if one facet of football is optional at best.

Oh, there was that time when the Hoosiers last won the Big Ten title with a defense that yielded an average of only 14.5 points per game in earning a spot in the Rose Bowl.

Of course, that was in 1967.

The past 50 years have mostly been marred by Indiana’s opponents often scoring almost at will, such as two seasons ago when the Hoosiers lost games in which their offense scored 52, 41 and 41 points.

Don’t assume, however, that the same old tissue-soft defense will line up for Indiana on Thursday night when No. 2 Ohio State opens its season with a Big Ten game in Bloomington.

Indiana returns nine starters to a defense that improved its average yards allowed per game more from 2015 to 2016 than any other team in college football, going from 509.5 (ranking 120th in the nation) to 380.1 (ranking 45th).

The turnaround in 2016 came in Tom Allen’s first season as Indiana’s defensive coordinator, leading to the Hoosiers’ 6-7 record and second consecutive bowl appearance, which hadn’t happened since 1990 and ’91.

In a twist of fate, Allen is now Indiana’s coach, and Thursday he’ll match wits with the guy who hired him a year ago: Kevin Wilson, the Buckeyes' offensive coordinator after serving as Hoosiers coach the previous six seasons, going 26-47.

“(Wilson) is a good coach, but we’ve got a pretty good defense,” Indiana senior quarterback Richard Lagow said. “It’s going to be a great matchup.”

The Hoosiers are led by Tegray Scales, a senior from Cincinnati who last season became Indiana’s first All-American at linebacker since 1987 while topping the Big Ten in tackles (126) and leading the nation in solo tackles (93) and tackles for loss (23.5).

Senior cornerback Rashard Fant is the cornerstone of the secondary, which returns all four starters from 2016. He is the NCAA’s active leader — and Indiana record-holder — in career pass break-ups (44) and passes defended (48).

Ohio State knows well why Indiana improved from No. 126 in pass defense in 2015 to No. 53 a year ago, finishing ninth in the nation in passes defensed (77) and 11th in completion percentage allowed (52.5).

Quarterback J.T. Barrett completed only 9 of 21 passes for 93 yards in last season’s 38-17 win over the Hoosiers. The Buckeyes won with 290 yards rushing, led by Barrett’s 137 on a career-high 26 carries.

Allen, serving as his own defensive coordinator this season, changed the Hoosiers’ fortunes by installing a funky 4-2-5 scheme and altering the defense’s mindset.

“First of all, we made such a huge issue of taking the ball away,” said Allen, who came from South Florida. Allen made himself and his players do 25 pushups if they say the word “turnover” because the term “takeaway” is more aggressive.

Indiana didn’t exactly morph into the 1985 Chicago Bears last year. The Hoosiers still allowed 27.2 points per game to rank No. 57, but that was dramatic improvement from No. 116 in giving up an average of 37.6 points in 2015.

If anything, the Indiana defense isn’t expected to roll over Thursday as it too often did in Wilson’s first five seasons, which included a 34-27 loss to OSU in 2015 and a 52-49 Buckeyes victory in 2012.