The longest, most arduous road trip of the Toronto Maple Leafs’ young season was supposed to provide clarity.

How good is this team — the one Vegas odds-makers had pegged as the Stanley Cup favourite just two weeks ago — really?

Well, after Saturday’s decisive 6-4 loss to the St. Louis Blues, arguably the best team in hockey, Toronto fell to 1-3 on their road swing.

Since being temporarily christened championship favourites, Leafs have dropped six of eight, all in regulation — and you’d be hard-pressed to argue that they’ve deserved a better fate.

Toronto has now surrendered five or more goals in a game six times, or 40 per cent of all outings. That’s the second-most in the NHL.

Against an organized, aggressive Blues squad that wanted it more, the Leafs got outworked, outsmarted, out-chanced and outplayed.

“It looks like they’ve got a real good hockey team with lots of swagger and playing well,” Leafs coach Mike Babcock said.

It’s been a minute since he’s been able to say the same about his own club.

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After the Leafs’ scorching start, the humbled, line-juggled group sits only one game above .500.

Here are six takeaways from the final game of Toronto’s reality-check road swing out west.

Babcock should have challenged

Maybe it was because the score was already so lopsided, 5-2, or because there were only 12 minutes left to play, but for some reason Babcock did not challenge the third-period Alex Pietrangelo goal that put the Blues up 6-2.

Centre Brayden Schenn appeared to have interfered with Toronto goalie Frederik Andersen on the play, but Babcock opted to save his timeout instead of throwing the flag:

“I don’t know what the issue was,” Andersen told reporters post-game. The goalie said he was interfered with a little bit. “I don’t know if we could challenge it. We’ll have to see after. It was a tough goal.”

That the Leafs scored two goals and narrowed the gap after Pietrangelo strike means the score might’ve been 5-4 with seven minutes left to play. Who knows what could’ve happened with the goalie pulled?

Borgman hops on the board, again

Even in a decisive loss — and there have been more than a couple of those over the past 10 days — we can pluck out the positive.

Undrafted rookie Andreas Borgman, who earned a roster spot by out-performing countryman Calle Rosen in October, opened the scoring in a tight first period when he accepted a nice Matt Martin cross-ice pass and picked Jake Allen’s top right corner with a 40-foot wrister off the rush.

The pretty snipe marked the defenceman’s second National Hockey League goal (both on this trip) and juiced the visitors with a spark of optimism to carry into the dressing room after 20 minutes.

“He was our best D,” Babcock told reporters. “He’s a competitive guy. I thought he had a good trip and he’s getting better all the time.”

Rebounds, blue line contributions turn the tide

The Blues owned the second period from start to finish.

First it was the always-dangerous Vladimir Tarasenko easily tapping in a rebound bobbled by Andersen after the puck took a nasty ricochet off James van Riemsdyk’s stick, and the game was tied just 2:33 into the frame.

Tarasenko now has seven goals on the year and has scored in six straight games versus the Maple Leafs.

Next it was Joel Edmundson, who was left alone and unchecked at the doorstep. So when a Schenn shot bonked in and out of Andersen’s glove, the defenceman had no issue depositing it in the back of the net.

Blues captain Pietrangelo scored the onslaught’s most beautiful goal.

Cutting in from the point after taking a pass during one of the Blues’ purposeful cycle shifts, the early Norris candidate burnt van Riemsdyk’s coverage, faked a shot (complete with leg kick), froze the goalie, then tucked the puck backhanded past Andersen as he edged around the back on the net.

“That was a great play,” said Joe Pietrangelo, Alex’s father, who was interviewed on-air from the stands.

Pietrangelo would add a second goal in third period (the unchallenged one) and now has six in a season that has made Blues fans totally cool with trading Kevin Shattenkirk. (As a Western Conference point of comparison, offensive D-men Dustin Byfuglien and Brent Burns have zero goals between them.)

Pietrangelo leads all NHL defencemen in scoring with 15 points, and the Blues’ 17 goals from the blue line ranks them No. 1 leaguewide.

Maple Leafs much too mushy in middle periods

Beginnings and endings are fine. It’s what happens in the middle of hockey games that undoes the Maple Leafs.

Sloppiness in its own zone became epidemic for Toronto in the second frame, as a series of Leafs giveaways and the Blues’ ability to dominate through a smart, determined cycle game led to three goals.

Through 14 games this season, Toronto is still a plus team, but the Leafs’ minus-10 goal differential in the middle frame ranks them worst in the entire league in Period 2.

“We didn’t have enough jump and enough juice and enough legs by any means,” Babcock said. “The game got out of hand, obviously.

“We made it look closer, probably, than it was at the end, but we’re fortunate the trip is over.”

Third period opens with a flurry

Eighty-two seconds into the final period of the Leafs’ disappointing road trip, Magnus Paajarvi pounced on a fumbled Nazem Kadri clear in front of Andersen’s net.

Stop us if you’ve heard this before, but another Leafs turnover in their own zone led to a goal.

“It’s not good enough, starting with myself,” Kadri told reporters. “I know I’ve got a lot better than that.”

In quick response, Tyler Bozak beat a spun-around, out-of-position Allen on a feed from Mitchell Marner, which snapped both Bozak’s goal slump and Marner’s point drought at five games.

But Vladimir Sobotka responded right back for the home side, and an exchange of three goals in a span of 62 seconds gave the Blues a cushy enough lead to withstand the inevitable…

Leafs last gasp

Connor Brown and Bozak (again) scored in the latter half of the third. Fourth-liner Martin had a personal-best night, production-wise, notching a career-high three assists on and leading the visitors in puck possession (69.2 per cent).

“Marty is not going to make three better plays than he made tonight,” Babcock said.

Alas, it was a case of too little too late.

This is becoming a familiar refrain for a Toronto team that is finding it increasingly difficult to outscore its mistakes.

“Everyone talks about the goaltender, and I think it’s more us than anything,” Martin said.

“You can only give up so many chances right in front of the net. We just hang him out to dry and don’t really give him a chance. We’ve got a lot to clean up.”

Home ice, and another chance to tighten up defensively, awaits Monday when the Maple Leafs host the Vegas Golden Knights for the first time.

“It was a tough swing,” said Martin. “A lot of good teams over here, and I think it’s a real wake-up call for us.”