But second-half tries from Rooney, Tony Martin and Sam Obst saw Wakefield complete a stunning comeback.
Australian-born Millard's exit follows the departures of Sam Obst to Hull FC and Dale Ferguson to Huddersfield.
Vince Mellars, Tony Martin and Peter Lupton went in for Crusaders but two Sam Obst tries compounded their misery.
Hello, He Lied: The title of Lynda Obst's Hollywood memoir could have described a corporate world once as glittering, in Houston.
And the home pressure paid off after 14 minutes when Obst scampered over in the corner from a Glenn Morrison offload.
It spurred Wakefield on and Obst completed an amazing comeback which included three tries in 10 minutes to level the scores.
Without eight regulars through injury and suspension, Wakefield were indebted to Drew and fellow playmakers Sam Obst and Scott Grix on Sunday.
New York - Hello, He Lied: The title of Lynda Obst's Hollywood memoir could have described a corporate world once as glittering, in Houston.
The pair touched down in the space of five minutes to hand the Wildcats control after Sam Obst and Jordan Thompson had traded first-half tries.
But scores from Epalahame Lauaki, Sam Obst, Jordan Turner and Kirk Yeaman, all improved by Danny Tickle, gave Hull their first away win of the season.
However, any thoughts they had of coasting to a win were cast aside when Lauaki burst over and, soon after, Obst crossed after good work from Sean Long.
Wellens was then at fault in the 31st minute when he allowed Sam Obst to weave his way past him and cross the line for a fine individual try, which Brough again converted.
Obst's score in the corner brought up the half-century for the visitors after the hour passed and in the closing 10 minutes Martin and Lupton went in for Crusaders before Obst grabbed his second try for Hull.
With Deacon off, Hull's former Wakefield half-back Sam Obst was a constant thorn in Wigan's side with his elusive running and his break set up the position for second rower Westerman to force his way over for an equalising try.
With a weakened squad, and expected to suffer the league's statutory six-point penalty for any club going into administration, the loss of Obst, Ferguson and now Millard - all three of whom started in Saturday's season opener against local rivals Castleford at the Millennium Stadium in Cardiff - are a huge blow to Wakefield coach John Kear.
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