A team many would have characterised as more than capable of mounting a tilt for second place in the SPL post-Rangers look increasingly like bottom six material.
While Caley Thistle were exceptional as they recorded their first SPL victory and clean sheet of the campaign, United looked low on confidence, energy and intent.
Rangers' absence, of course, has heaped new pressures and expectations on managers' shoulders and few have taken quite the battering locally that Terry Butcher, the Inverness manager, has endured in recent weeks.
A perceived prejudice against local and Scottish players has added to scepticism among supporters, but yesterday those 3000-odd in attendance would have surely glimpsed what Butcher has been trying to create.
The Englishman's post-match assessment was laden with a hint of relief as well as obvious pleasure at an important win.
And there was, justifiably perhaps, a sense of vindication thrown in for good measure.
"I thought we dominated the game and played some lovely stuff – and could have scored more goals," the home manager stressed. "I'm just really pleased for the players because they have put a real shift into this season.
"We are a difficult team to beat – we're unbeaten now in eight out of 10 matches this season. And we're on a four-match unbeaten run which is a world record for us.
"The style of the game and the manner by which we won it was very impressive, too. The players have taken a lot of hassle this season from people who have written them off, but they can certainly play.
"We all knew they had this performance in them. The perfect answer is to keep winning matches and climb the table. "
With goalkeeper Ryan Esson injured in the warm-up, Caley Thistle were slow to find their feet. United snapped at their heels early on and Jon Daly was uncharacteristically wasteful in one golden opportunity after only four minutes.
When the hosts did catch fire, the result was spectacular. Richie Foran, back to his best in a striking role after holding fort deep in midfield last season, was to take his personal tally to four in five league games.
The Dubliner scored with a splendidly placed right foot from the angle of the box after 31 minutes. Just three minutes later, Foran met a cross from the excellent on-loan Arsenal teenager Philip Roberts at the back post for the second.
After the break, the home dominance only intensified and United were a bedraggled and dispirited bunch as Andrew Shinnie battered through their rearguard to hit the third.
Roberts, a real talent in the making it would seem, then rattled the top of the net spectacularly from the corner of the box.
"If there is a self-destruct button to hit, we certainly know how to hit it," Houston said later. "I felt in the first 25 minutes before the first goal we were the team in the ascendancy and looking dangerous going forward.
"We lose a good goal from Richie Foran but a pass from Sean Dillon in the centre of the park was cut out.
"The second we should defend better at the back post. We allowed crosses into the box and from then on it was a mountain to climb.
"The second half display was extremely poor. It is a huge disappointment for the United fans and we apologise for that.
"It was an embarrassing performance in the end. To lose 4-0 away, just isn't good enough. I apologise to the fans."