While the former Manchester United midfielder believes the Chilean will prove a good buy, he says it does not solve the Gunners' 'biggest problem.'
The former Man United and England man believes Sanchez will prove a good buy but feels the Gunners need Sami Khedira - or a centre-back - more.
As such, Scholes believes Arsenal will be 'a bit soft' without them and even went as far as labelling them 'the same old Arsenal' - capable of scoring goals and playing good football but struggling psychologically in bigger games.
"As for the other big arrivals in the Premier League, I believe Alexis Sanchez for Arsenal will be a good signing although I am not sure it goes to the heart of the issues they face," Scholes wrote in the London Evening Standard.
"I appreciate Sanchez is a really good attacking player but they have a lot of players like that already. Arsenal’s biggest problem is that they need a tough midfielder.
"If they can sign Sami Khedira or even a strong centre-half, I think Arsenal will go close in the title race. But without having that I think they could still be a bit soft.
"Arsenal will score a lot of goals and play some nice football. The same old Arsenal. But when it comes to Chelsea, Manchester City, United in the big League matches I still think they will struggle psychologically to handle those games."
The north London side open their Premier League campaign against Crystal Palace this afternoon.
Tony Pulis left Palace on Thursday night, perhaps putting Arsenal in the perfect position to capitalise.