Smith reckons new chief scout Sven Mislintat, who worked with Aubameyang at Dortmund, has played a big part in the deal.
“I wouldn't say it was a vital signing, they've got (Henrikh) Mkhitaryan in to replace (Alexis) Sanchez, they've got (Alexandre) Lacazette but he's got his problems at the moment," Smith said on Sky Sports.
“It will give a boost to the club and the dressing room, at a time where I think they probably need one after last night.
“He's a quality player, very pacey player that's always looking on the shoulder and he's got a great goalscoring record. A bit lively off the pitch, he's had one or two issues.
“That's not always an Arsene Wenger player, so maybe it suggests he's not totally in control of what's coming in these days.
"They've got Sven Mislintat, who used to work at Dortmund, as head of recruitment.
“Maybe he's pushed that through, he sees that as a really good signing.
"I wouldn't disagree if they could get him in."