Though the Swiss squad lie eighth in the constructors' championship, they have scored 36 points in total and in six of the last eight races - a stark contrast to their barren run during what was their worst ever season in 2014, when they failed to record a single top-ten finish.
"I didn't really know what to expect," Ericsson confessed when asked about his expectations at the start of the year.
"Sauber is a team with a great history but also Sauber had a very difficult year last year so when I joined it was absolutely not clear what it would be and were we would start from.
"To be honest it outperformed my expectations - we have been points candidates in almost every race."
Ericsson believes the team will be in an even stronger position in 2016, in part due to the benefit of continuity from retaining the same driver line-up.
"I think it will be better as it will give stability to the team," Ericsson added.
"We know now the in's and out's; we know the working procedure; and we know the mentality. We are both very involved in next year's car - speaking with the engineers about what we want from the car."
With two races to run, Ericsson currently sits 18th in the drivers' championship, on nine points. His best result remains the eighth place he secured in the Australian season opener, a race in which team mate Felipe Nasr finished fifth - Sauber's best result in nearly two years.