Downey's score, which kick-started the Saints' 33-3 win, came at the end of the first passage of play in the game and involved several pairs of hands from forwards and backs.
The Irishman will be up against six other players for the award, which will be handed out at next Tuesday's Aviva Premiership Rugby Awards in London.
The scores came from a long list of tries selected by supporters at the end of each Aviva Premiership Rugby round and whittled down to the final six by a panel of media professionals.
The shortlist is:
1. Christian Wade London Wasps v Leicester Tigers
2. Jonny May, Gloucester Rugby v Harlequins
3. Luke Wallace Harlequins v London Wasps
4. Michael Claassens, Bath Rugby v London Irish
5. Alesana Tuilagi, Leicester Tigers v Northampton Saints
6. Freddie Burns, Gloucester Rugby v Exeter Chiefs
7. James Downey, Northampton Saints v Exeter Chiefs
The shortlist was selected by a panel of - Jill Douglas (Freelance), Miles Harrison (Sky Sports), Alastair Eykyn (5Live), Mick Cleary (Daily Telegraph), Ian Stafford (Mail on Sunday), Nick Mullins (ESPN), David Rogers (Getty Images), Alan Pearey (Rugby World). They were joined by Corin Palmer (Premiership Rugby's Head of Academies and Development) and Paul Morgan (Premiership Rugby's Communication Director) who chaired the panel.