Out-of-favour playmaker Metcalf was unavailable for Saturday night's 30-12 win over his future club, having missed training this week to finalise his move.
A serious knee injury to his usual replacement Tanah Boyd looked to have cleared a path for Metcalf to once again become a starting half from next week.
But things might not be so simple after halfback Martin crossed for two tries and played a hand in two others at Jubilee Stadium, where sections of the crowd booed the Dragons at full-time.
"He did, honestly, a terrific job," Warriors coach Andrew Webster said of Martin.
Webster would not confirm his halfback for next Sunday's blockbuster against ladder-leading Penrith.
"While the team's winning, people are going to deserve their spot, but I'm not doing any selection stuff tonight," he said.
Saints gave up three restarts and a penalty ahead of Martin's first try, scored as the halfback dummied inside Hayden Buchanan.
He had a second try six minutes after the break, shrugging out of Clint Gutherson's tackle and then bolting past Josh Kerr.
Martin combined with Chanel Harris-Tavita ahead of Alofiana Khan-Pereira's second try, with the five-eighth throwing a great ball on the left to confirm his winger's double.
Dallin Watene-Zelezniak sealed the win, and his own double, picking off a Luciano Leilua pass and running 20 metres to score untouched in the last 10 minutes.
The second-placed Warriors' sixth straight win came without State of Origin stars Kurt Capewell and Mitch Barnett, and despite mid-game injuries to Roger Tuivasa-Sheck (knee) and Eddie Ieremia-Toeava (head knock).
The twin blows meant Jackson Ford switched to second row in his first game since being snubbed from NSW State of Origin selection.
After losing Jaydn Su'A (calf) at captain's run, the Dragons had to contend without his replacement centre Buchanan, whose shoulder began popping out early in the first half.
The Warriors cashed in; four of their six tries came against a makeshift right edge that had Gutherson defending at centre.
Compounding Saints' woes, veteran hooker Damien Cook limped off in the final minutes with an apparent ankle issue.
"It's a bit sore at the moment ... hopefully it's nothing serious," Cook said.
The Dragons managed the first try of the game thanks to a flat pass from Dan Atkinson to Hamish Stewart, who slipped a one-handed offload to Setu Tu.
But red-zone execution and 16 errors haunted the Dragons thereafter.
"We started the game pretty good, we went six from six (sets) and started well. From that point I think we were at 61 per cent (completion rate)," said interim coach Dean Young.
"That's going to make it really, really hard against the sides that are down the bottom of the competition, but it's nearly mission impossible against the side that's coming second."
The Dragons are now on the outright second-longest losing streak of the NRL era, behind only Newcastle's dismal 19-game slide that ended in early 2017.
