The Gunners managed just one shot on target in the match but that was enough for victory, as Noni Madueke's deflected strike with ten minutes remaining earned them three points.
Madueke came on at the break to replace Eze, who got the nod to start on the left wing but failed to take his opportunity.
In his 45 minutes on the pitch, the No10 did not manage a single shot or successful dribble. He also did not create a chance.
Chance missed: Eberechi Eze
Getty
Asked what convinced him that Eze needed to be replaced at the interval, Arteta said: "The way they were defending.
"The two units outside, the two-vs-twos they were creating without having real threat in behind. Forcing [Daniel] Munoz into a different kind of game, they were more comfortable.
"So that's why we have the players with different qualities and adapt to what the game is delivering."
Madueke was bright on the left wing last weekend against Leeds and he made the difference at the City Ground to drag Arsenal past a stubborn Forest defence.
He now looks favourite to keep hold of that shirt as he battle with Eze continues in the absence of Christos Tzolis.
Game changer: Noni Madueke
PA
Eze had been positive in midweek. He scored in the Champions League win over Lille and showed enough to keep his place against Forest, but he struggled to make any sort of impact in his 45 minutes on the pitch.
"Three days ago, he scored a goal, should have scored three and we were all happy," Arteta said.
"This is football. One day it's brilliant, the next day [it's not]. Especially for attacking players against a team that defends with ten players in and around the box, the No9 dropping almost at the edge with that Christmas tree [shape].
"It's extremely difficult but that's why you need fresh legs, different profiles and to try different things."