One of the most exciting prospects in English football, Dack was voted the League One Player of the Year by the Football League and FourFourTwo magazine in a matter of weeks in the spring of 2016.
The attacking midfielder, who initially joined the Gills on trial in March 2009 upon his release from Charlton Athletic, scored 26 goals for the youth team in the 2011/12 season. He made his first substitute appearance for the club in the Capital One Cup win at Championship side Bristol City in August 2012, before his full league debut came a week later against Wycombe Wanderers.
Dack signed a four-year contract extension at the MEMS Priestfield Stadium in April 2014, having become a first-team regular. He scored five goals in all competitions during the 2013/14 season, and doubled that tally to 10 the following campaign.
He was the driving force behind the Gills' promotion push throughout the 2015/16 season, scoring 15 times and providing 12 assists, form that attracted attention from numerous Premier League and Championship clubs. Dack won five awards at the club's annual end of season dinner in May 2016, including Player of the Year, Young Player of the Year and the MEMS Player of the Year.