Moses showed no sign of easing off on his return to club duties after inspiring the Blues to a 38-18 win over Queensland in Melbourne on Wednesday.
The playmaker scored two tries and had a hand in two more at McDonald Jones Stadium on Saturday, but he could not stop the Eels falling to a third consecutive loss.
Origin hero Mitchell Moses celebrates one of his two four-pointers for the Eels. (Gregg Porteous/AAP PHOTOS)
The Eels are last on the NRL ladder with just one win since mid-April.
"There were opportunities that we just didn't quite finish, again," said interim Eels coach Trent Barrett.
"We just couldn't really get any luck at all."
Parramatta looked set to buck their ugly run of form when some quick-thinking Moses kicking forced a goal-line drop-out, with Blaize Talagi bagging the opener on the ensuing set.
Debutant Knights five-eighth Will Pryce - watched on by his father, English great Leon Pryce - hit back for Newcastle after a Daniel Saifiti offload in heavy traffic.
Moses touched down off a scrum play to restore the Eels' lead before Greg Marzhew barged his way over to have the hosts trailing 12-10 at halftime.
Knights winger Marzhew and Talagi both scored early into the second half before the two sides had tries chalked off by the bunker.
Newcastle centre Bradman Best failed to ground the ball and Talagi, who was hunting a hat-trick, was ruled to have knocked on in the process of touching down.
This try effort was unsuccessful, but Bradman Best scored two long-range tries for the Knights. (Gregg Porteous/AAP PHOTOS)
Parramatta also had a first-half effort from Maika Sivo effort rubbed out after replays failed to show he grounded the ball on the line.
"Sometimes you get them, sometimes you don't, but it seems at the moment we are on the wrong side of a few (calls)," Barrett said.
"It's hard on the players, we're running out of players, we've got a lot of injuries and players playing out of position."
Moses took matters into his own hands, surging down the left in the 60th minute to add his second try.
But Newcastle pulled away in the final quarter of an hour, a runaway try from Best and a close-range finish from Enari Tuala ensuring Junior Paulo's 75th-minute finish counted for little.
Best, who missed NSW selection for game one with injury, put the icing on a victory for Newcastle when he ran 60m with 90 seconds left.
The win leaves the Knights knocking on the door for the top eight, denied a spot by virtue of their inferior points differential.
Knights coach Adam O'Brien praised Best.
"Being able to run the length of the field but improvement with Greg (Marzhew) on that left edge defensively was outstanding," said O'Brien.
"He was dealt a pretty bitter pill to swallow (missing Origin), I think he would have been in the game one team.
"To not drop his bundle and come back and get in the form he's in is a credit to him. He's still a young man, Bradman."
2°C