Penn State football opened its biggest coaching position available on Monday. Tom Allen pulled the stunner by leaving his defensive coordinator post for Clemson.

The now ex-DC jams from one College Football Playoff qualifier to join another. Allen's move comes one day after star edge rusher Abdul Carter declared for the 2025 NFL Draft.

So PSU now must replace its best defender and defensive coordinator at the same time. The era of the transfer portal and recruiting makes replacing Carter easy. Head coach James Franklin and company, though, get the hard part: Finding the right coach to lead this defense.

This position rises as the best defensive coordinator job in the Big 10 Conference. Who looks like the prominent candidates? Here are the top replacement options.

Al Golden, Notre Dame defensive coordinator 

Nov 16, 2024; South Bend, Indiana, USA; Notre Dame Fighting Irish defensive coordinator Al Golden watches warmups before a game against the Virginia Cavaliers at Notre Dame Stadium. Mandatory Credit: Matt Cashore-Imagn Images
Matt Cashore-Imagn Images

Siphoning Golden can ease the hurt of the Orange Bowl loss for Penn State.

Golden helped construct the defensive plan that slowed down the high-powered Penn State offense. Drew Allar threw only 135 yards. The explosive running back duo of Kaytron Allen and Nicholas Singleton failed to reach 100 yards. And the latter got forced to settle for only red zone touchdowns.

The 55-year-old, though, would receive a homecoming if hired as Penn State DC. He played for the Nittany Lions from 1988 to 1991. Golden also coached linebackers in 2000 at PSU.

Elijah Robinson, Syracuse defensive coordinator 

Dec 27, 2024; San Diego, CA, USA; Washington State Cougars quarterback Zevi Eckhaus (4) runs the ball against Syracuse Orange defense during the second half at Snapdragon Stadium. Mandatory Credit: Abe Arredondo-Imagn Images
Abe Arredondo-Imagn Images

Throwing in another past PSU defender. The 39-year-old also once lined up on the offensive line for the Nittany Lions.

Furthermore, Robinson earned his coaching start in State College — going from graduate assistant to defensive line coach in 2011. He even served as director of community relations for Penn State.

The Orange, however, fell to 14th overall in defense among Atlantic Coast Conference teams. Syracuse also allowed the fourth-most points among the 17 ACC members. But Robinson still has deep ties to the school. He also coached in the Southeastern Conference by leading the Texas A&M defensive line and briefly taking over for Jimbo Fisher as interim head coach.

D'Anton Lynn, USC defensive coordinator 

USC Trojans defensive coordinator D'Anton Lynn reacts against the Utah State Aggies during the fourth quarter at United Airlines Field at Los Angeles Memorial Coliseum.
Jonathan Hui-Imagn Images

We have one more former Nittany Lions star to monitor. Lynn starred at cornerback from 2008 to 2011.

The CFB world now knows Lynn as a red-hot young coordinator. He lifted UCLA to rank No. 11 in total defense for the 2023 season. Lynn later improved USC's defense by slicing the scoring. The Trojans went from fielding the nation's 121st ranked scoring defense in '23 to rising to 57th.

Lynn would be in for this third straight coaching stop since 2023. But PSU can bring a former Nittany Lion home.

Kevin Coyle, former Fresno State defensive coordinator

Mar 3, 2019; Tempe, AZ, USA; Atlanta Legends head coach Kevin Coyle against the Arizona Hotshots during an AAF football game at Sun Devil Stadium. Mandatory Credit: Mark J. Rebilas-Imagn Images
Mark J. Rebilas-Imagn Images

Now it's time to look into a surprise name. But a coordinator who makes a lot of sense when you dive into the credentials.

Kevin Coyle didn't just produce one of the top defensive units in the Mountain West Conference. He comes with a deep resume that includes NFL stops.

Coyle spent 2001 to 2011 with the Cincinnati Bengals as their defensive backs coach. He later ran the Miami Dolphins defense from 2012 to 2015 during a period Cameron Wake and Brent Grimes led the unit. But moreover, Coyle has deep east coast ties that should win over PSU — as he's from Staten Island, New York and coached at Holy Cross and Syracuse.

Johnny Nansen, Texas co-defensive coordinator 

Arizona football players advocate for Johnny Nansen as new head coach

Nansen emerges as an outside hire in a similar breath as Coyle. Except his Cotton Bowl and past work could win over Franklin.

Nansen joined Pete Kwiatkowski in limiting explosive Ohio State wide receiver Jeremiah Smith to only one catch for three yards last Friday. PSU can pick his brain on how to bottle Smith in the coming years by hiring him. But Texas built the SEC's best defense in its first season as a full-fledged conference member — with Nansen overseeing the linebackers.

Nansen became beloved at Arizona in assisting Jedd Fisch with the Wildcats' 10-3 turnaround of 2023. Franklin and PSU hands him the full defensive reins here if brought over.

Elsewhere, Penn State has internal options to choose from if the Lions don't want to conduct a national search. Anthony Poindexter served as co-defensive coordinator in Happy Valley for four seasons while also leading the safeties. Jaquan Brisker and Ji'Ayir Brown turned into future day two NFL Draft picks under him. Poindexter comes with past DC experience, spending 2014 to 2016 leading UConn's crew.

Deion Barnes is one last option, but within Franklin's staff. Barnes' coaching spearheaded the stellar 2024 campaign from Carter. He'd get promoted from defensive line coach.