The Gunners boss is coming under increasing pressure at the north London outfit following their slow start to the season.
Arsenal are in sixth position in the Premier League table and eight points adrift of defending champions Manchester City in fourth spot.
The north London outfit signed Nicolas Pepe in a £72m deal from Ligue 1 side Lille in the summer.
However, the Arsenal record signing has struggled to hit the ground running at the Emirates Stadium, while Emery’s defence has conceded 17 times in 12 games.
Emery has attempted to leave his mark on the Gunners since the Spanish head coach was appointed as Arsene Wenger’s replacement.
Former Arsenal defender Upson believes Emery has made a number of mistakes at the north London club since his appointment 16 months ago.
“A loss to Southampton [following the international break leaves [Emery] in real limbo because I think he’s struggling,” Upson said BBC Radio 5 Live.
“I was at Leicester [before the international break] and I saw a really poor performance from Arsenal.
“It was almost like they tried to cater to not get beat at Leicester who were on top form, and this is Arsenal, and never really got any kind of grip of the game.”
Questioned about whether Emery had lost the Arsenal dressing room, Upson added: “Maybe, maybe that’s the case, maybe there’s already a loss of belief or whatever it may be in the manager.
“Emery came to the club and he tried to change things, he tried to be more disciplined. Again you have to look at the recruitment, don’t you?
“To spend what they have spent on an attacking wide player, with the other issues that need to be addressed in the team…”
Arsenal signed six new players in the summer transfer window, including Chelsea FC centre-half David Luiz and Celtic full-back Kieran Tierney.
However, the Gunners have still struggled defensively to undermine their goal threat up front.
Arsenal have only managed to win one of their last six Premier League games to heap pressure on Emery.
The north London side will welcome Southampton to The Emirates on Saturday afternoon.
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