Tom Allen has held various defensive coaching positions throughout his career, contributing to significant improvements in the defensive performances of multiple teams. Here’s an overview of his tenures and the defensive achievements at each institution:
Wabash College (2007): • Position: Special Teams Coordinator/Secondary Coach • Achievements: Wabash won the North Coast Athletic Conference championship and advanced to the quarterfinals of the NCAA Division III playoffs. Allen coached three defensive backs who earned All-NCAC honors and tutored the team’s first-team All-NCAC punter. 
Lambuth University (2008-2009): • Position: Assistant Head Coach/Defensive Coordinator/Linebackers Coach • Achievements: In 2009, Lambuth’s defense ranked fourth nationally in scoring defense, seventh in pass defense and sacks, ninth in total defense, and 12th in third-down conversions. The team achieved its first undefeated regular season (11-0) in 2009. 
Drake University (2010): • Position: Defensive Coordinator/Linebackers Coach • Achievements: Drake’s defense allowed just 330 yards per game, ranking sixth nationally in rush defense (94.2 yards per game), eighth in sacks (33), and 25th in scoring defense (20.4 points per game). 
Arkansas State University (2011): • Position: Assistant Head Coach/Linebackers Coach • Achievements: The Red Wolves led the Sun Belt Conference and ranked in the top 25 nationally in total defense (331.5 yards per game) and scoring defense (20.8 points per game). They also averaged 7.6 tackles for loss per game (8th nationally) and 2.7 sacks per game (15th nationally). 
University of Mississippi (Ole Miss) (2012-2014): • Position: Linebackers Coach/Special Teams Coordinator • Achievements: In 2014, Ole Miss led the nation in scoring defense, allowing just 13.8 points per game, and permitted the fewest total touchdowns (18). The Rebels ranked 13th nationally in total defense (321.2 yards per game) and 11th in tackles for loss (7.5 per game). 
University of South Florida (2015): • Position: Defensive Coordinator • Achievements: USF’s defense led the American Athletic Conference in scoring defense during league play, allowing 19.6 points per game. Nationally, they tied for 13th in tackles for loss (7.5 per game), 14th in interceptions (17), and 24th in takeaways (25). 
Indiana University (2016 - Defensive Coordinator; 2017-2023 - Head Coach): • Achievements as Defensive Coordinator (2016): Indiana’s defense improved significantly, allowing 372.6 total yards per game compared to 509.5 yards per game in 2015. Points allowed per game decreased from 37.6 to 27.3.  • Achievements as Head Coach: In 2020, Indiana’s defense played a pivotal role in the team’s 6-1 regular-season record, achieving a top-10 ranking in the AP poll. The Hoosiers led the Big Ten in interceptions and were among the national leaders in takeaways.
Penn State University (2024): • Position: Defensive Coordinator/Linebackers Coach • Achievements: Penn State’s defense ranked seventh nationally in total defense (294.7 yards per game) and eighth in scoring defense (16.5 points per game). They also finished ninth in rushing defense, allowing just 101.8 yards per game. 
Throughout his career, Tom Allen has consistently elevated the defensive performance of his teams, leading to nationally recognized defensive units and contributing to overall team success.
Seems like he will do well with the level of talent Clemson can provide him. Leagues above what he's accustomed to. However, it may take effort for Nick Eason, Chris Rumph, and Mike Reed to make that all happen.
Our country won't go on forever, if we stay soft as we are now. There won't be any America because some foreign soldiery will invade us and take our women and breed a hardier race.
~Chesty Puller
Lt.General United States Marine Corps