This time last year losing to Norwich City left Arsenal eighth in the table and many supporters suggesting Arsène Wenger's days in the dugout were numbered. Now this thrilling victory, featuring goals that Wenger described as "close to perfection", has reinforced their position at the top of the table and everyone is looking up to the manager again.

The record purchase of Mesut Özil just before the closure of the transfer window has been seen as a major turning point, and the German reinforced that view with two splendid goals, but the non-purchase of a new striker may have been equally pivotal. Wenger believes his failed attempts to sign Gonzalo Higuaín and Luis Suárez could have triggered the improvement in Olivier Giroud.

"That was maybe a little bit his luck," says Wenger of the aborted transfers. "Nobody came in, so you know at the start of the season that at least you get the chance to show how good you are. I always thought that his second season would be the decisive one. We have seen that many times – to adapt to the kind of game we play takes time. I was not too worried when we didn't bring anyone in because I thought he had a chance to develop."

Giroud had a good debut season in the Premier League last term but this season he has flourished, becoming not merely a fulcrum and a finisher but also a creator as intricate as the artists around him. Özil, Aaron Ramsey and Jack Wilshere scored delightful goals while Giroud set up two of them and regularly joined in their ingenious interplay.

"Giroud is amazing because he develops well," says Wenger. "If you compare his technical level when he arrived to how it is today, he has highly improved. Now he enjoys combining much more. From a player who was just thinking 'I have to score', he has become a real team player."

In light of how many players have improved – Ramsey and Kieran Gibbs have also reached new heights – and how many will soon return from injury, including Theo Walcott, Alex Oxlade-Chamberlain and Lukas Podolski, Wenger says he may not need to buy in January. "We have a squad that, number and quality wise, is very good," he added.

"We are not desperate to sign anyone in January. If there is a good opportunity, then why not? But at the moment, when you know who is out and that they will come back in November and the beginning of December, then you have a really massive squad."

Massive, but how well balanced it is remains to be seen. Norwich showed when Jonny Howson scored that Arsenal are still defensively vulnerable, especially when Mathieu Flamini is not in midfield to shield the back four. He suffered concussion in the first half and may miss Tuesday's Champions League meeting with Borussia Dortmund. And, although Nicklas Bendtner looked dangerous when he arrived as a substitute, it is by no means certain that he could do what Giroud does if the Frenchman were missing for long. Wenger knows he may still need to reinforce in January.

Forthcoming fixtures may confirm that. Arsenal's start has been superb but so far they have beaten only one team who are currently in the top half of the table. Tougher opponents await. Recent history, too, must weigh on the manager's mind. The last time Arsenal were top of the league after eight matches was in 2007-08, when they appeared on course for glory until a collapse from mid-February to mid-April left them out of all competitions. A January injection might help avoid a repeat of that, providing an Özil-esque stimulus. Then again, not recruiting then might inspire players à la Giroud.

Chris Hughton, meanwhile, has more pressing problems at Norwich. He needs to win soon. After his normally frugal employer spent some £30m in the summer, a return of two victories from eight league matches has put the manager under pressure. "It is a concern," admits Hughton. The chairman, Alan Bowkett, declared earlier this month that a top-10 finish would be a realistic return on the club's investment but Hughton says his targets are not quantifiable.

"What we've always said is that we want to finish this season and feel that the squad has improved and we've grown as a club and the academy has made good strides. Those are the most important things. At no stage have we said about finishing in a certain position or getting a certain number of points."

Man of the match Olivier Giroud (Arsenal)

• This article was amended on 21 October 2013 to correct the name of the Norwich chairman, Alan Bowkett.