Despite losing talisman Gareth Bale in the summer, a flurry of big-money signings meant there was an air of excitement at White Hart Lane.
However, too many of the new additions failed to hit the ground running and Spurs' poor performances led to Andre Villas-Boas' sacking in December.
Things have been hit and miss under successor Tim Sherwood, but Sunday's remarkable 3-2 comeback victory over Southampton has given them a glimmer of hope.
Sigurdsson's late winner means Spurs are just seven points behind fourth-placed Arsenal and, while accepting it is their rivals' to lose, the midfielder admits failure to secure a Champions League berth will cap a frustrating campaign.
"It will be a disappointment if we don't finish higher than fifth," he said. "We brought a lot of players in last summer and we know it's going to take time.
"It depends on some of the players coming in - some of them fit in straight away, some need a few months or a season just to get used to English football. That's life. If we can finish in the top four, it will be fantastic.
"Would continuity help us for next season? I don't see why not. There are fantastic players here and we have good staff all around.
"If we start next season well, then everything is possible. Most of the new players will be in their second season so they will be used to English football by then and they will have settled in."
This is Sigurdsson's second season with Spurs, having rejected the overtures of Liverpool to move to north London in 2012 - a decision he may now regret given how things stand.
Brendan Rodgers' side are just a point off leaders Chelsea and will look to maintain their title charge with an eighth successive league victory when Tottenham head to Anfield on Sunday.
The Reds will be buoyed by their 5-0 win at White Hart Lane earlier in the season - a match which did not make pleasant viewing for substitute Sigurdsson.
"We want to win every game, especially after the way we lost to them here last time," he said of the game that cost Villas-Boas his job.
"We're on a mission now to get as many points as we can. It's important for us to get at least one point, if not three.
"The key for Liverpool has been the form of Daniel Sturridge and Luis Suarez.
"The way they have been playing is a result of the goals they have been scoring, which give the team a lot of confidence. Brendan Rodgers has them playing very well."