Assistant manager Mark McGhee is pleased with the progress Scotland are making but thinks performances may need to improve in order to reach Euro 2016.
The Scots are third in Group D, with 10 points from five matches.
"All we've done is achieve what would have been expected," said McGhee. "We've not done better than that.
"To qualify, we're probably going to have to do a little bit better - look at the coming fixtures and look at what the possibilities are."
Sunday's 6-1 victory against Gibraltar leaves Scotland one point behind section leaders Poland, who were held 1-1 by a last-minute Republic of Ireland goal.
"If you looked at the fixtures at the start of the campaign, you'd have seen Georgia at home, Republic of Ireland at home, and you'd have hoped we'd win those games," McGhee told BBC Radio Scotland.
"You'd look at Poland away and think maybe we can sneak a draw - and we did.
"You'd look at Germany and probably say we won't get anything there - and now we've beaten Gibraltar."
Scotland's next fixture is a trip to Dublin in June, with Martin O'Neill's side two points behind in fourth place.
|Scotland's remaining qualifying fixtures|
|Republic of Ireland (a) 13 June 2015|
|Georgia (a) 4 September 2015|
|Germany (h) 7 September 2015|
|Poland (h) 8 October 2015|
|Gibraltar (a) 11 October 2015|
"I think it's a must not lose game for them," McGhee said of the short journey across the Irish Sea. "There is still a lot to happen.
"The trip to Georgia is not straightforward. Germany went there yesterday and won 2-0, which is a good result, but not a huge result.
"Georgia are not whipping boys and they will still have a say.
"You'd probably say we have to go to Georgia and win. That would be a fantastic result, regardless of Ireland doing it. Ireland stole that result in the last minute.
"That is going to be a huge game for us."
Scotland started with an unusual formation against Gibraltar, with manager Gordon Strachan using just one central defender, flanked by two full-backs.
And the Hampden crowd was temporarily stunned on 19 minutes when Lee Casciaro fired in an equalising goal.
"I think the squad is improving all the time, regardless of the performance against Gibraltar," added McGhee.
"We did plenty of work on the system but it didn't quite manifest itself in the way we hoped. We expected to get in a lot more crosses and get behind them more.
"It was a bit disappointing but it got us four goals [before an extra central defender was added at half time].
"Gordon wants to entertain. He wants the punters to enjoy it, he doesn't want to play a stagnant, defensive game.
"In going the way we went; it wasn't exactly gung-ho but it was exciting.
"Germany scored four, Ireland scored seven against them. Had we played the way we expected, we could have had more than that.
"We scored six and maybe you could say we mugged them. We just had better players, instead of the silky football that we were looking for."