After all, the Irishman had not just endured 90 minutes chasing them forlornly around Tannadice but he also spent much of the summer on trial with Jackie McNamara's squad only for the extraordinary development of Andy Robertson to stymie his hopes of earning a contract.
Subsequently, the 24-year-old signed for Ross County and on Saturday was part of a limited team who lost for the seventh time in eight games. Given the corollary in that United recorded a sixth consecutive victory, it would be understandable if Carey harboured a little envy, but instead the midfielder was more than willing to eulogise those who he had hoped to call team-mates.
It was entirely in keeping with the respectful manner in which County evaluated this contest: manager Derek Adams talked of their hosts being in a "different league" and of being content to have "kept the scoreline down" after setting up his team to dig in and hopefully pinch a point. Perhaps that was understandable given the fearful towsings United had administered while scoring 21 goals in their last five games but it was also an insight into what McNamara's side are likely to come up against in the second half of the campaign.
United monopolised the ball and forced 21 corners on Saturday but were, for the most part, thwarted in their attempts to play their way through County, who sat deep and smothered any attempts at intricate attacking. The hosts' feted front four were subsequently suffocated, but a combination of patience, persistence and a little luck when Scott Boyd slipped enabled them to record the win that moves them into second place in the SPFL Premiership.
Within that there are two aspects that merit closer examination. United did not play particularly well yet still eked out a victory, a rare quality in a side so inexperienced. "This is the kind of game we might not have won last season so it shows how far we've come," said midfielder Stuart Armstrong, who also revealed he did not initially believe his side were capable of finishing second in the division this season because of such inconsistency.
Carey echoed that opinion, citing the youth of the group, but both he and Armstrong have since altered their stance. "Being so young has worked to their advantage as they're fearless," said the County midfielder. "Training with some of the young lads you could just tell they were going straight to the top and there's more coming through, which is the scary thing. It's going to be tough and they could run out of steam but they have such quality in the team and on the bench. They probably have the strongest squad outside of Celtic."
That McNamara could summon substitutes Nadir Ciftci and David Goodwillie to try to break County down speaks to that, but to dwell once again on United's attacking capabilities overlooks the fact they boast the joint-best defensive record in the table. McNamara's side, so porous last season, have conceded just 12 times in 17 matches.
Gavin Gunning and John Souttar have established a central defensive partnership that compensates for its physical deficiencies with speed of thought and movement and the ability to build play from the back, and they are protected by holding players Paul Paton and John Rankin. The latter, especially, has been in magnificent form. "Their best four players on Saturday were the two central defenders and the two sitting midfielders," said Carey. "They are all so comfortable on the ball. The two midfielders get overlooked because the flair players are doing such great things but they allow the rest of the boys to go and express themselves."
On Saturday, County could rely on similar shows of strength by their own centre-backs and holding midfielders but lacked the flair, or perhaps just the ambition, to cause United problems. Carey's deliveries fleetingly gave the hosts pause for thought - in particular one free kick that reared up and off the bar - but the Dingwall side struggled to cleave open genuine opportunities. On this evidence, Derek Adams' team face an attritional struggle to avoid finishing in the relegation play-off place.
The manager has talked of strengthening his hand next month but finding a regular source of goals will not be easy. "It would be good to get bodies in but we have quality in our team and I just think we're not using it to our full advantage," said Carey. "We're not taking chances and every mistake we make we seem to be gifting goals to teams. We need to pick ourselves up because it will take hard graft and luck to turn things around."