SEATTLE — The defending champion Seattle Sounders did not storm out of the gate in 2017.

Not like Toronto FC did.

“We had some dark days,” said Sounders head coach Brian Schmetzer after Thursday night’s 3-0 (5-0 aggregate) romp over the Houston Dynamo in the Western Conference finals of the MLS playoffs. “We had some games where we weren’t really playing well, or up to our potential.”

The teams meet on Dec. 9 at Toronto’s BMO Field in a rematch of last season’s MLS Cup, but the Sounders’ path back to the final was markedly less certain.

While Eastern Conference champion Toronto ran rampant from start to finish in a record-setting regular season campaign, the Sounders fell to 2-5-4 in mid-May after losing three straight by a combined score of 8-1.

A championship hangover — which Schmetzer has repeatedly acknowledged — is more reality and less excuse in a league that begins training camp some six weeks after the league final.

Injuries along an aging back line also prevented Schmetzer from fielding his first-choice defense until the 15th game of the season. Over those 15 games he was forced to deploy 10 defensive units, with no back four taking the field together more than three times.

Problems in attack abounded, as second-year forward Jordan Morris struggled to find the back of the net and the team struggled to integrate Clint Dempsey back into the group after his return from an irregular heartbeat.

Seattle began to right the ship in midsummer, but yet and still often seemed something short of a legitimate threat to repeat as league champions.

“Yes, we learned that we had a lot of resilience,” Schmetzer said in late August after the Sounders found a stoppage-time goal to beat Minnesota United, “and we’re always looking to be on the front foot to score goals. But we also have to reflect back on the soccer. Is the soccer good enough for the playoffs?”

That was indeed the question for much of the season, and for much of the season the answer seemed anything but certain. Even though the Sounders have lost just twice since July 4, there was also a winless month of soccer from late August to late September, when the club posted an 0-1-4 record. A promising win would be followed by a relatively listless draw.

But then came the home stretch and the playoffs. The soccer has been good enough and then some. Since Sept. 23 the Sounders are 6-1-1, have outscored opponents 14-2, and have posted six straight shutouts. Goals are coming from everywhere, but Dempsey — that legendary U.S. international absent for all of last year’s playoff run — has delivered four goals and two assists over that stretch.

“We are finding ourselves in a better part of the streak than we were last year,” said goalkeeper Stefan Frei after Thursday’s win.

In the conference finals, particularly in the second leg, the one- and two-touch passing was crisp and swift and intelligent. Midsummer signing Victor Rodriguez has been a revelation in midfield, pairing superior vision and technical skills with a penchant for making quick and aggressive decisions in attack. Cristian Roldan and Nicolas Lodeiro appear ever more comfortable together in midfield, and Will Bruin has delivered a goal and an assist in the last two games.

“All the goals tonight were very, very good goals,” said Schmetzer.  “Well crafted, good soccer plays.”

Asked if he thought the attack was hitting its stride, the second-year head coach did not hesitate.

“Sure,” said Schmetzer. “Getting Victor (Rodriguez) back (from injury) was key. (We’re) getting Clint back in a good place. Will is doing well. Nico today from a deeper position today was fantastic. I think Cristian was great. (Joevin Jones) has been tremendous. The attack is looking pretty good.”

For most of 2017 conventional wisdom has said the MLS Cup trophy is likely headed to the Eastern Conference. But pair a resurgent attack with a defense that has not allowed a playoff goal in a record-shattering 647 minutes — the 2002 New England Revolution held the previous record at a suddenly paltry 374 minutes — and it’s clear why the Sounders seem confident about their chances in Toronto.

“Our last two games were some of the best games we’ve played,” said Frei, “and I think that bodes well for next week.”