Treacy booted 4.3 and reeled in 12 marks in a commanding performance which exceeded the stats sheet, as the hosts overcame a wayward start to run out 60-point winners at Optus Stadium.
The key forward's sticky hands are among the most reliable in the AFL and were a beacon in slippery conditions on Saturday.
"He's a competitor. There's not many players at our club that work harder on their game than JT," Fremantle coach Justin Longmuir said after the 13.25 (103) to 6.7 (43) win.
"He's evolved in all areas. He looks for improvement in all areas of his game, hence he's fitter, he's stronger and his craft is better than last year, and his last two years have been really strong as well.
"He gets a lot of balls kicked into his hands and then when everyone is finding it slippery, he's marking like a dry-weather day.
"I don't want to give all his secrets away. He just does the reps ... it's just consistent application to a process, and you become better at your craft."
The focal point of a stacked Dockers forward line, Treacy was well assisted by Jye Amiss (two goals) and Patrick Voss, while Andrew Brayshaw and Caleb Serong were typically industrious in the midfield.
Shai Bolton drove repeat forward entries, including a sublime gather on the wing to set up an Amiss goal.
Another key weapon at Justin Longmuir's disposal, ruckman Luke Jackson, was also influential in the second half after going into the midfield and roaming forward, while Isaiah Dudley's pressure and tackling were outstanding.
Torrential rainfall had been forecast as ex-Tropical Cyclone Narelle tracked south, with young Tigers forward Seth Campbell pictured jokingly sporting swimming goggles at Friday's training session in Perth.
The rain largely held off beyond sporadic showers, although both teams had forgettable moments with a slippery Sherrin.
Richmond showed their rebuild is well and truly on track during an impressive first half, despite having lost almost 600 combined games of experience with injuries to Toby Nankervis, Nathan Broad and Tom Lynch.
With acting skipper Tim Taranto (24 disposals, 10 tackles, two goals) relishing the greasy conditions, the Tigers led shortly before halftime but couldn't stay with a Fremantle side gunning for an elusive premiership.
"To play against a really strong side on their home deck, hostile environment, tough conditions ... I couldn't ask for any more," Richmond coach Adam Yze said of the first half.
"We looked like we just lost our way a little bit in the second half, which is disappointing."
Powerful Richmond young gun Sam Lalor was among the best afield in the first half, while Steely Green slotted three goals.
The result leaves the Tigers on an eight-game losing streak and one of two teams still winless this season.
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