The striker did eventually net his fifth goal of the season in the 25th minute to give Crew the lead.
Justin Meram doubled Crew's lead in the 52nd minute when he beat the offside trap to finish from close range.
Ethan Finlay confirmed the win with Crew's third as McInerney played him in to tap in to an empty net.
The 25-year-old added a fourth just a minute later when he turned past Taylor Kemp and beat Hamid.
Aaron Schoenfeld added a fifth in the 79th minute when he slid in to divert a cross into the net.
Finlay thought he had sealed his hat-trick in stoppage time but Hamid came out to parry the ball behind.
DC United will host New England Revolution in the playoff knockout round next week.