The Gunners signed the Gabon international in a club record £56m deal from the Bundesliga giants in the January transfer window.
Aubameyang was brought in to help replace Alexis Sanchez after the Chile international completed a swap move to Manchester United.
The 28-year-old scored on his first Arsenal start in a 5-1 win over Everton in the Premier League at The Emirates at the start of February.
However, the African forward missed a penalty in a 3-0 loss to Manchester City in the English top flight in north London last week.
Aubameyang scored his second Premier League goal in Arsenal’s 2-1 loss to Brighton and Hove Albion at Amex Stadium on Sunday afternoon.
Former Arsenal striker Smith admits Aubameyang is already struggling at the north London club.
“He looked a shadow of the player he was at Dortmund,” Smith told Sky Sports. “Even he, in the short time he’s been at Arsenal, has been affected by the mood.
“He got his goal with a little flick, but he’s not the player I hoped he would be. I’m not saying he’s a bad player, but it’s a malaise through the dressing room and he’s been affected.
“We haven’t seen anything from [Henrikh] Mkhitaryan in an Arsenal shirt yet and this is when you need your big players, in an attacking sense, to get you back into a game.”
Aubameyang scored 141 goals in 213 games in all competitions during a five and a half season stint at Dortmund.
Arsenal are in sixth place in the Premier League table and 13 points behind fourth-placed Tottenham Hotspur.
The Gunners signed Aubameyang’s former Dortmund team-mate Henrikh Mkhitaryan as part of the swap deal that saw Sanchez move to Manchester United.
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