The Wantage Road side secured second place in Division Two on Wednesday.
"It's a very different club from when I walked through the door," Smith, who was appointed in December 2011, told BBC Radio Northampton.
"There's a different coach. A different environment. I never worried about what had happened in the past."
Northamptonshire have never spent more than one successive season in the County Championship Division One
In head coach David Ripley's first full season in charge, Northants ended their nine-year exile from the County Championship's top flight, with Essex's failure to pick up maximum batting points against Hampshire sealing their promotion.
It means the final two days of Northants' fixture against Worcestershire will have no bearing on the make up of Division Two's top two.
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