Arsenal played out a goalless draw with champions Leicester City on Saturday after losing their opening game against Liverpool at the Emirates Stadium earlier this month.
With the Gunners still searching for their first win of the season, Wenger has come under increasing scrutiny from the fans and the media for his lack of investment into the squad, which finished second last campaign.
"I quite admire that, in the world where some clubs have so much money, they go and buy players who are £40m and are worth £10m," Vieira, who captained Wenger's last title-winning team in 2004, told British media.
Wenger has made three additions to his squad during the current transfer window, bringing in midfielder Granit Xhaka, defender Rob Holding and striker Takuma Asano.
"But on the other side the team is not doing as good as it used to and you need to win football matches," added Vieira, who manages Major League Soccer side New York City FC. "They've been disappointing, losing games they should have won.
"My generation had lots of physically strong players. In this last five or six years, Arsenal went more with this type of mobile, technical players.
"Now when I watch Arsenal, yes they play good football but I just have a feeling they are missing something - the physical presence, the personality, this is what they're missing."
Manchester United spent £89m to bring back Paul Pogba from Juventus and Vieira hoped the France midfielder will not crumble under the pressure of the tag of being the world's most expensive player.
"I think he's a fantastic player, no doubt about it, but I also believe the Premier League is different, and there will be a lot of pressure on his shoulders because of the price tag and expectation," Vieira said.
"He will have to find the right balance because if he thinks he will win games by himself that will be a massive mistake for him, if he tries to do something that he can't do that will be a massive mistake as well."