ST. LOUIS — You can feel this whole thing starting to become very tenuous, a situation where the final epitaph might read “They overachieved for a good while and were a fun little story, but when it was time to play with the big boys, these Colorado Avalanche just weren’t ready for prime time.”

You can feel, as the stat geeks like to say, that the regression to the mean is in full swing, that these Avs just don’t look quite well-equipped enough to make a real, genuine run at a playoff spot. Tuesday’s 3-1 win over the San Jose Sharks at home is looking more like the aberration now, amid a stretch of hockey where these guys just haven’t played very well. Even in that win over the Sharks, it felt kind of fluky.

There was nothing fluky about their showing Thursday night at the house of horrors otherwise known as Scottrade Center. The Avs just flat-out looked like they didn’t belong on the same ice as the bigger, tougher St. Louis Blues. The 6-1 embarrassment puts the Avs at 2-4-1 since that already-distant seeming 10-game win streak.

Granted, this team has a very good excuse for not being at its best of late. They have been without their superstar leading scorer, Nathan MacKinnon, since Jan. 30. But even in the two games the Avs played before he got hurt – losses to Montreal and the Blues – signs of regression to the mean were starting to creep in again.

Thursday was kind of the exclamation point on two weeks of very mediocre play, and you can sense that these guys know they’re in some real trouble entering the final third of the season. MacKinnon or not, some real problems have risen to the surface again, such as:

• Jared Bednar just can’t figure out any good combination to form an effective second line. Even when MacKinnon was playing, the Avs couldn’t find any reliable trio behind the top line. Thursday night, it was Colin Wilson’s turn to center the second line, with Tyson Jost and J.T. Compher. And, it was a disaster. Wilson, making $4 million this season and next, had no shots on goal, couldn’t complete or accept a pass and was bad defensively – being way out of position on St. Louis’ third goal, for example.
• The third line, led by center Carl Soderberg, is going cold. Soderberg has no points in his last seven games, and he was a minus-3 in this one.
• Nail Yakupov played like a top spinning out of control in his brief time on the ice, and has generally fallen off the face of the earth scoring-wise for a while now. He has one goal in the last 17 games.
• Tyson Barrie hasn’t looked the same since returning from a cracked bone in the right hand, Erik Johnson is starting to look a little worn down from playing so many minutes and the loss of depth defenseman Mark Barberio has hurt worse than people might have thought.
• The schedule-maker might be the Avs’ biggest enemy of all right now. They go from here to Carolina, then Buffalo, for back-to-backs this weekend. They come home for another token game or two, then go right back out for another grueling Canadian road trip. Not only are they on the road a ton this month, but the schedule is just weird geographically. St. Louis, Carolina and Buffalo, three games in four nights? Thanks, NHL.

And now, for perhaps the most distressing note of all: the goaltending. Hey, it just wasn’t Jonathan Bernier’s night in this one, and he’s been mostly great overall, even in the losses of late. So, he gets a pass here. Though, let’s face it, he did not look good in a big game against a division team.

The bigger worry, to me, has been the play of Semyon Varlamov since coming back from injury. I thought – and so did other people around the team – that he looked slower in his start in Winnipeg, not tracking the puck very well. He sure didn’t look good in relief of Bernier against the Blues. He looked reactive, not proactive, in playing shots.

If Varly can’t find close to his old form, this becomes a team in the hands of a journeyman goalie on just a one-year deal, who can become an unrestricted free agent this summer. What if he decides to jet off to greener pastures, and the Avs are left with an oft-injured veteran goalie who has lost his confidence? That could stall the progress I think this team otherwise will keep making as some young players continue to mature, and guys like Cale Makar and Conor Timmins get closer to joining the club.

Look, the future I think is bright for this team. Let’s face it, nobody thought they’d be this close to a playoff spot even this far into the season. Maybe this team has more moxie and perseverance than I’m giving them credit for here. Maybe they’ll get MacKinnon back soon and go on another run again.

But that’s not going to happen if some of those other problem areas are addressed. Otherwise, the looming takeaway for this season is going to be:

“It was fun while it lasted, but it’s over now.”