The Tannadice side came into the festive season riding high on a run of six successive wins.
But their incredible hot streak was dowsed by a 4-1 Boxing Day defeat to St Mirren, St Johnstone's 3-0 win last Sunday and a last-gasp defeat to Aberdeen on New Year's Day.
Young recruits like Ryan Gauld, Andrew Robertson, John Souttar and Stuart Armstrong were praised to the high heavens for their displays during that unbeaten run which saw Jackie McNamara's side blast 22 goals.
All four were off the pace, however, as the Dons' kicked-off 2014 with a 2-1 win after Peter Pawlett grabbed a last-minute winner.
But Rankin insists their fluctuating form is not the only reason why United have gone off the rails.
He said: "My experience of playing with young boys is that they are up and down. That's just the way it is. They can find it hard to get a steady level of performance.
"But I thought Soapy [Souttar] was great getting his goal against Aberdeen and I don't think we should be singling out the younger lads for blame.
"It is a team effort and there are 11 guys who took responsibility for that defeat.
"Rado had to make a couple of good saves to keep us in it and we snatched at a couple of chances near the end when we could have shown a bit more composure."
The Terrors sat second in the Scottish Premiership on Christmas Day but three successive defeats now leaves them in fifth, trailing Motherwell - who took their slot behind leaders Celtic - by eight points.
Rankin's old club Hibernian are due at Tannadice on Sunday but the 30-year-old is insistent United can rediscover their best form.
"It doesn't get any easier," said the former Easter Road midfielder. "Hibs are a massive club with good players.
"They are coming off the back of a derby win and have now grabbed the bragging rights for the city.
"But if we can get back to the standards and tempo that we have set before the last three games then there is no reason why we can't get the three points.
"If we can go on a similar run to the one we've just had, we can get back up the league again.
"The disappointing thing is that we've now lost three on the bounce but it's about reactions now. We were getting plaudits when we were winning games, but we have to show the other side of our make up, that we can bounce back."
United lost Keith Watson and Calum Butcher to red cards in the defeats to the Saints from both Paisley and Perth, while Robertson claims he was harshly punished for a handball in the box as Aberdeen's Barry Robson was handed the chance to level Souttar's opener from the penalty spot on Wednesday.
Now Rankin is keeping his fingers crossed United get a fairer hearing from Steven McLean when he takes charge of Sunday's fixture.
"The Aberdeen defeat was a bitter pill to swallow," he said. "We didn't do enough to win it but then I didn't think we deserved to lose either.
"It was a big decision which has changed the game again. Andy says that for the handball incident, the ball has come up and hit his chest.
"But it was still 1-1 at that point and we had all to play for, so it's disappointing we lost out.
"We've not had much luck with referees these past few games but I suppose they even themselves out over the season. Hopefully later on we will get the benefit of the doubt."