Tuncay Sanli scored both goals at Villa Park, taking his tally to three league goals as Southgate believed his front men started to improve.
"Tuncay made a big difference to us when he came back into the side after injury," Southgate was quoted as saying by The Northern Echo.
"He has three now this season, Alves has three and Mido has five, so the players up front are starting to produce."
Mido missed the game with injury and he will need up to two weeks to recover.
Boro are now in the eighth place on 17 points.
They will have to fight to keep their spot in the top half of the table when playing seventh-placed Everton, Bolton and then Hull City, who come sixth, in the upcoming weeks.
Midfielder deal
Meanwhile, Boro have announced the signing of 17-year-old Slovak midfielder Peter Gal-Andrezly on loan from MFK Kosice.
Andrezly impressed on a recent trial at Rockliffe Park, as he will join Boro reserves in January.