Iowa defensive coordinator Phil Parker has a challenge ahead of him this season, but not one he’s necessarily unfamiliar with.

The Hawkeyes’ defense allowed only 14 points per game last season — fifth-best in the FBS. But going into the 2020, Parker has a lot of holes to fill in the lineup.

All-Big Ten defensive lineman A.J. Epenesa was selected in the 2020 NFL Draft, and so were defensive backs Michael Ojemudia and Geno Stone. Iowa’s leading tackler from last season, linebacker Kristian Welch, graduated, as did defensive tackles Cedrick Lattimore and Brady Reiff.

By now, Parker is used to losing starters from one season to another. Let’s see if he can produce another elite defense this season.

Defensive line

 Senior Chauncey Golston takes over for Epenesa as Iowa’s top pass rusher. Epenesa produced double-digit sack totals in both of the past two seasons, while Golston has 6.5 sacks in his entire Hawkeye career.

Golston isn’t expected to match Epenesa’s production — few could. But the preseason second-team All-Big Ten pick is a versatile pass rusher who can move along the defensive line and create mismatches.

Iowa’s other starting defensive end could be either Zach VanValkenburg, Joe Evans, or John Waggoner. Evans was second on the team with four sacks last season, while Waggoner and VanValkenburg also rotated in on the defensive line.

On the interior of the defensive line, Daviyon Nixon and Austin Schulte should see a bump in playing time with the departures of Lattimore and Reiff. In his first year seeing the field as a Hawkeye, Nixon tallied 5.5 tackles for loss and three sacks.

Graduate transfer Jack Heflin, a second-team All-MAC performer in 2019, is a projected starter at defensive tackle for Iowa. The 6-foot-4, 312-pounder led Northern Illinois in sacks (three) and tackles for loss (8.5) last season.

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Linebackers

 Rob Howe of HawkeyeNation.com reported on Monday that Iowa linebacker Djimon Colbert will opt out of the 2020 season and return to the Hawkeyes for his junior season in 2021.

Colbert was Iowa’s starter at weakside linebacker the past two seasons and finished 2019 with 61 tackles. The Hawkeyes were already lacking experience prior to Colbert’s decision. Welch is now on the practice squad of the Baltimore Ravens and Dillon Doyle transferred to Baylor earlier this summer.

Senior Nick Niemann has started at outside linebacker for much of the past two seasons, but Iowa’s move to a 4-2-5 defense and the implementation of the cash safety has often removed the Leo linebacker from the field. Niemann may take over the role as starting middle linebacker this season or could remain on the outside.

Jack Campbell showed potential that he could start at linebacker in the Big Ten as a true freshman last season but wasn’t consistent enough to stay on the field. Senior Barrington Wade and redshirt freshman Jestin Jacobs could also be competing for playing time.

 Secondary

 Matt Hankins, a senior, takes over the role as Iowa’s top corner in 2020 with Ojemudia’s departure. Junior Riley Moss or sophomore Julius Brents will likely start at corner opposite Hankins.

Jack Koerner found his way into Iowa’s secondary early last season and his play on the field made it tough for Parker to ever take him out. As a redshirt sophomore last season, Koerner — a former walk-on — started 11 games at free safety and was second on the team with 81 tackles and also finished the season with an interception and five passes defended.

Either Dane Belton or Kaevon Merriweather could replace Stone and start at strong safety for Iowa this season. Belton played the cash position in subpackages in 2019 as a freshman and may do that again in 2020. Merriweather was a starting safety to begin last season before an injury forced him out of the lineup and Koerner won his spot.