In just four seasons on Wisconsin’s coaching staff, Jim Leonhard has managed to further elevate a defense that has become one of the nation’s best, year in and year out.

He is in his fourth year as defensive coordinator, and fifth on staff overall, in 2020.

Few could be considered more knowledgeable about having success on defense at Wisconsin than Leonhard, a 2015 inductee to the UW Athletic Hall of Fame who was one of the most successful players to ever patrol the Badgers’ defensive backfield.

Following his retirement from a 10-year career in the NFL, Leonhard joined the Badgers’ staff as defensive backs coach in 2016. He became defensive coordinator less than a year later and went on to be named a finalist for the Broyles Award, presented to the nation’s top assistant coach, in his first season running UW’s defense.

With Leonhard on staff, Wisconsin’s defense has quite simply been one of the nation’s most complete and high-performing units.

Over his first four seasons, the Badgers ranked third in scoring defense (17.2 points per game), fourth in total yards allowed (297.9 yards per game), fifth in rushing defense (112.3 ypg) and fifth in pass efficiency defense (109.0). Wisconsin forced the second-most turnovers of any FBS team during that span, with 104, and the Badgers’ 68 interceptions also ranked No. 2 nationally.

In 2019, Leonhard’s unit posted four shutouts — the first Big Ten team to do so since 1962 — and set a school record by allowing opponents to convert just 27.2% of their third-down attempts. Led by 12.5 from consensus All-America outside linebacker Zack Baun and 11.5 from All-Big Ten inside linebacker Chris Orr, the Badgers smashed the school record with 51 sacks on the season.

In its first year under Leonhard’s direction in 2017, the Badgers’ defense ranked second nationally in total yards allowed (262.1 ypg), third in scoring defense (13.9 ppg), third in rushing defense (98.4 ypg) and No. 1 in pass efficiency defense (96.4).

Led by the Leonhard-coached secondary, UW gave up just 11 touchdowns through the air, picked off 20 passes and was one of only four FBS teams to hold opposing teams under a 50 percent completion rate. With a school-record 75 breakups to go along with their 20 interceptions, the Badgers led the nation with 95 passes defended.

Cornerback Nick Nelson, a consensus first-team All-Big Ten selection and second-team All-America pick, led the way with a school-record 21 pass breakups. Remarkably, 10 players recorded at least one interception for the Badgers — led by four apiece from senior safety Joe Ferguson and junior linebacker T.J. Edwards — with a school-record five picks returned for touchdowns.

Edwards and junior safety D’Cota Dixon joined Nelson as first-team All-Big Ten picks, leading the way for an impressive list of 11 players who earned all-conference recognition for their efforts on the Badgers’ league-leading defense.

Key to the Badgers racking up a school-record 13 wins, including a victory in the Orange Bowl, UW’s defense allowed just 18 touchdowns in 14 games.

Leonhard’s impact on the Badgers’ secondary was immediate in 2016. His unit was instrumental in the Badgers grabbing 22 interceptions, a total that ranked second in the FBS and marked UW’s highest output since 2002, when Leonhard himself recorded a school-record 11 of UW’s 22 picks.

The secondary contributed to an overall effort that saw the Badgers finish ranked No. 4 nationally in scoring defense (15.6 ppg), No. 7 in total defense (301.4 ypg), No. 3 in rushing defense (98.8 ypg) and No. 10 in pass efficiency defense (106.9).

Under Leonhard’s tutelage, senior cornerback Sojourn Shelton was named first-team All-Big Ten for a season in which he recorded four interceptions and 12 pass breakups. Senior safety Leo Musso, the Badgers’ MVP, finished with a team-high five picks, while fellow safety Dixon grabbed four and Tindal had three at corner.

A product of tiny Tony, Wisconsin, Leonhard arrived on campus in 2001 as an unheralded, 5-foot-8 walk-on and left four years later as a three-time first-team All-American. He played in every game of his four-year career, including each of the last 39 as a starting safety, en route to becoming one of the best defensive players in school history.

He matched UW’s school record with 21 career interceptions, the fourth-most in Big Ten history, and finished with 50 passes defended — 25 of which came during his breakout sophomore season in 2002. His nation-leading 11 interceptions that year tied the Big Ten’s single-season record.

Leonhard earned first-team All-America laurells that season and became the first sophomore to be named Wisconsin’s team MVP since 1947.

The following season, Leonhard proved those numbers were no fluke, again being named a first-team All-American. He led the Big Ten with eight interceptions, including a key fourth-quarter pick in Wisconsin’s 17-10 upset of No. 3 Ohio State, and tied for the team lead with 98 tackles. He also returned two punts for touchdowns and broke his own school record with 470 punt return yards.

As a senior, Leonhard again earned first-team All-America honors and was a finalist for the inaugural Lott IMPACT Trophy.

He finished his career with 21 interceptions, tying Jamar Fletcher’s school record. He also broke the Big Ten record with 1,347 career punt return yards.

Leonhard excelled in the classroom, as well. A two-time CoSIDA Academic All-American, he also was a finalist for the William V. Campbell Trophy, the prestigious National Football Foundation award referred to as the “Academic Heisman.”

Though he went undrafted, Leonhard put together a 10-year NFL career with Buffalo, Baltimore, the New York Jets, Denver, New Orleans and Cleveland. He played in 142 games as a pro, starting 73 of them. He made 14 career interceptions and averaged 9.2 yards per punt return.

He earned a spot on the Bills’ 53-man roster after signing as an undrafted free agent and spent three seasons in Buffalo, playing in 38 games.

Leonhard got his big break in 2008 after signing with the Ravens. He started 16 of Baltimore’s final 17 games, including all three in the playoffs. He signed with the New York Jets the following season and started 40 games over the next three seasons. He then played for the Denver Broncos in 2012 and the Bills again in 2013 before retiring following the 2014 season with the Cleveland Browns.

Leonhard and his wife, Katie, have three sons, Reese, Graham and Pierce.