ST. LOUIS – All year, the Yankees have prided themselves on winning games in any conceivable manner.

Close games, slugfests, times that required a balanced approach or needed a hero, from Aaron Judge - with three walk-off home runs - to an unheralded reliever.

Lately, "we've lost some of the games we've been winning all the time,'' said manager Aaron Boone.

And for a week now, the team’s championship belt, awarded to the player of the game after a victory, hasn’t moved from Anthony Rizzo’s locker.

“We’re definitely going through it right now,’’ DJ LeMahieu said after the NL Central-leading Cardinals completed a three-game sweep at Busch Stadium.

Sunday’s 12-9 Yankees loss – on the heels of Saturday’s 1-0 defeat – extended their losing streak to a season-high five straight games.

“We need to play better, to be quite frank,’’ said Josh Donaldson, after Frankie Montas’ Yankee debut went south and out-hitting the Cards 16-11 wasn’t enough.

“At the end of the day, we still feel good about our team,’’ Donaldson said of going through “a little slide right now. We need to get back on track.’’

Heading to Seattle, the Yankees’ next three games are against a playoff contender that took two of three games against them last week in the Bronx.

Jameson Taillon, Gerrit Cole and Nestor Cortes are lined up to face the Mariners.

And Tuesday brings a rematch between Cole and Luis Castillo, the No. 1 trade target by the Yankees until the Cincinnati Reds shipped him to Seattle for a better prospect package.

After envisioning Castillo riding shotgun with Cole into a postseason series, Yankees Universe watched Castillo tame the Yanks at the Stadium for the second time this season.

And they witnessed Cole’s worst inning, yielding three homers during a six-run first.

Since that game, the Yankees jettisoned Jordan Montgomery, sent to St. Louis for injured outfielder Harrison Bader (plantar fasciitis) because the lefty wasn't viewed as part of a postseason rotation.

Montgomery's five scoreless innings against the Yanks in Friday's St. Louis win was a karmic response.

Against the Red Sox at Fenway Park this weekend, the Yanks’ likely starters are Domingo German, Montas and Taillon.

It’ll be Montas’ first taste of The Rivalry, following a Yankees debut that misfired Sunday at steamy Busch Stadium.

“My mechanics weren’t in sync,’’ said Montas, who yielded a season-high six earned runs in just three innings. However, “my arm feels good.’’

In his third start back from shoulder inflammation, Montas (64 pitches) was on a limited pitch count, but doesn’t believe he should be restricted going forward.  

Montas hadn’t started since July 26, and he went on the bereavement list shortly after his trade from the Oakland Athletics for four prospects.

“It’s been a tough few weeks, but at the end of the day, I have to do my job,’’ said Montas, who was “really excited’’ about becoming a Yankee but disappointed Sunday.  

“I wanted to go out there and show them what I can do.’’

Anthony Rizzo said his status remains “day-to-day’’ due to lower back tightness, though he “feels better’’ than Friday, when he was a late lineup scratch.

How concerned should the Yankees be about this chronic issue?

Exactly a month ago, Rizzo missed four games due to a similar problem, and Rizzo repeated that it’s best to “just be smart’’ and not risk a worse injury.

Rizzo spent Sunday’s pregame going through elaborate stretching exercises, but “to be frustrated, that’s kind of a waste of time,’’ since he’s committed to “do what I need to do to recover.’’

Meanwhile, Giancarlo Stanton (strained left Achilles) has been hitting off a machine and conducting light running.

Later this week, the slugger is expected to begin hitting off live pitching.

Stanton might even arrive in Boston this weekend, but Boone does not want to put out a target date for his lineup return.

“Bottom line is, he’s trending in a good direction right now.’’