He added: "I think today was a very important result".
"They played with two strikers, Lacazette and Aubameyang and you think that would form a good partnership but not if you've not got the creativity in wide positions".
The Gunners stretched their unbeaten run to 21 games but had looked set to drop two points at the Emirates Stadium before Torreira's spectacular overhead kick seven minutes from time.
He has the quality and he has a very quick interpretation of the pitch in a tactical sense, both offensively and defensively.
So far Emery has coped fairly without his talisman. "But we have players", he said. We wanted to win this way playing with a bigger rhythm over 90 minutes, but they stopped our rhythm a lot over 90 minutes.
He said on the BBC's Final Score programme: "They aren't title contenders for me yet". We needed patience and to win by waiting for our moment.
This was an otherwise unremarkable game, the tempo slowed by the constant fouls, which resulted in nine yellow cards being handed out - including three to Arsenal players for diving.
Shkodran Mustafi limped off with with a hamstring injury, just three days after fellow centre-back Rob Holding ruptured a ligament in his left knee.
Emery's side returned to winning ways with a narrow 1-0 victory over Huddersfield Town at The Emirates on Saturday afternoon.
"It's a tough match for that because of the opposition, because they were stopping the play by fouling us in the circumstances".
Wagner refused to be downhearted, however.
On whether his players are becoming more adaptable in changing systems he admitted: "We are preparing differently and tactically".
"Unfortunately, we haven't got one, but we can keep our head held high after this performance against a top-class side". "Next Sunday we are going to find the best first XI". I did this last week and the week before, we always receive phone calls and they apologise after they've seen video footage.