Born in Oxford, Massachusetts, Herrion received his bachelor's degree in psychology from Merrimack College in 1989. As an undergrad at Merrimack, he competed in both basketball and baseball and worked as a student assistant coach in 1986–87. He also served two seasons as the junior varsity coach at Cambridge Ridge and Latin High School in Cambridge, Massachusetts. A native of Oxford, Massachusetts, Herrion was a three-year letterwinner in both basketball and baseball at Oxford High School. Herrion hails from a coaching family. His father, the late Jim Herrion, was a successful high school coach in the New York City Catholic League before becoming an assistant coach at Holy Cross and later the head coach at Worcester Polytechnic Institute. His older brother Bill Herrion is currently the head basketball coach at the University of New Hampshire. Bill has also served head coaching stints at both East Carolina and Drexel University.
Coaching career
Herrion's collegiate coaching experience includes assistant stints at the University of Virginia, Providence College and NCAA Division II Merrimack College. He spent eight seasons under Pete Gillen at both Virginia and Providence. In his four seasons at Virginia, Herrion helped Gillen orchestrate a 70–50 record and three postseason appearances. His main responsibilities included recruitment of student-athletes, scheduling and scouting of opponents and assisting with practice planning and game preparation. Additionally, the Cavaliers' recruiting classes were ranked among the nation's top-10 in three of his four seasons with the program. At Providence under Gillen, the Friars put together a 72–53 four-year record including a berth in the NCAA Tournament's Elite Eight and two NIT appearances. Herrion also served as an assistant coach at his alma mater, Merrimack College, from 1989 to 1994. During that time, he helped guide Merrimack to two NCAA Division II tournament appearances.
College of Charleston
As a head coach, Herrion spent four seasons at the College of Charleston. From 2002 to 2006, he compiled an 80–38 four-year record, earned a national top-25 ranking, guided his team to the 2003 National Invitation Tournament and achieved the best winning percentage in the Southern Conference during that period. His first Cougar team in 2002–03 finished 25–8, captured the Great Alaska Shootout title and advanced to the NIT. His 25 victories marked the highest total of any first-year NCAA Division I head coach during the 2002–03 season. Herrion also guided the Cougars to a 20–9 finish in 2003–04, an 18–10 performance in 2004–05, and a 17–11 record in 2005–06.
In the spring of 2007, Herrion arrived at the University of Pittsburgh as an assistant to head coach Jamie Dixon. He was later promoted to the position of associate head coach at Pittsburgh, where his main responsibilities included recruiting student-athletes, game preparation and on-floor coaching. Herrion assisted head coach Dixon in leading Pitt to the NCAA tournament during his three-year stint at the school that included a run to the "Elite Eight" in 2009, a year that saw the Panthers earn their first-ever #1 rankings in the AP Poll and Coaches' Poll, their first-ever victories over a #1 ranked team, and their first-ever #1 seed in the NCAA Tournament. During the 2007–08 season, Pitt also won the Big East Tournament. In the 2009–10 season, Herrion's final year as an assistant at Pitt, they lost to Notre Dame in their first Big East Tournament game, and concluded the season in the NCAA Tournament with a second-round loss to Xavier.
Marshall University
Herrion was announced on April 10, 2010 as the 28th head coach of men's basketball at Marshall University. In 2012, Herrion coached the Thundering Herd to the National Invitational Tournamentfor the first time since 1988. On March 14, 2014, Marshall announced it had bought out the remaining two years of Herrion's contract. Herrion went 67-67 in four seasons, but just 24-41 in his final two years. Marshall Athletic Director Mike Hamrick said "We just didn't win enough games." Herrion's buyout was around $550,000.
Georgia Tech
On September 18, 2014, Herrion was hired by Georgia Tech head coach Brian Gregory as an assistant coach.
TCU
On July 21, 2016, Herrion was hired by TCU head coach Jamie Dixon as a special assistant.
South Florida
On April 5, 2017, Herrion was once again hired by Gregory as an assistant coach, this time for South Florida.
