A veteran coach, he joined the Rensselaer staff from Dartmouth College, where he was an assistant from 2015-18.

In his first season in Troy, he led the team to a 12-win season (12-5) and a berth into the Liberty League Tournament Semifinals. The Engineers, who won their first six games and 9 of their first 10, were nationally-ranked for much of the campaign. Four student-athletes earned National All-America recognition and freshman Cooper Urban was the league's Rookie of the Year.

The 2020 season lasted only six games before being canceled due to the COVID-19 pandemic but RPI managed four wins with three coming on the road. A truncated 2021 campaign allowed for four games, which RPI won a pair despite a limited roster because of coronavirus-related restrictions.

While with the Big Green before taking over at Rensselaer, Hackett-Dalgliesh was a top assistant and recruiting coordinator, while also playing a role with budget preparation, fundraising and alumni relations.

On the field, he coordinated a defense that was nationally-ranked in saves and caused turnovers in 2016. He moved to the offense in his next two seasons, mentoring a unit that increased its productivity in several categories, including goals per game and points per season.

Hackett-Dalgliesh was an assistant coach at UMass Lowell for the 2014 season, the team's first as a Division I program. Prior to that, he was the head coach at Division III Marywood University for three years (2012-14), posting a record of 25-28 (.472), including a pair of 10-win seasons.

Hackett-Dalgliesh mentored 30 CSAC All-Academic student-athletes and 23 All-CSAC players while with the Pacers. He also served as coordinator of field operations, where he was the department's liaison in coordinating and scheduling practices and games.

He spent 2011 as an assistant at Brown University under the tutelage of head coach Lars Tiffany, and 2009-10 at Lafayette College, where he worked with 2010 Patriot League Coach of the Year Terry Mangan. Serving as a defensive coordinator, Hackett-Dalgliesh helped the Leopards to one of the most improved seasons in Division I on its way to a national ranking and the program's first appearance in the Patriot League Tournament.

A 2007 graduate of Dickinson College, where he earned a Bachelor of Arts in Law and Policy, Hackett-Dalgliesh played attack and helped set numerous conference and program records upon graduating.