Stassi had two impressive home runs among his four hits and Canning struck out 10 in six crafty innings to lead the Angels to a 4-2 victory Tuesday night.
The loss, plus St. Louis' 5-0 win at Kansas City, kept the Padres from clinching the NL's No. 4 seed in the playoffs and homefield advantage in the wild-card round next week. On Sunday, the Padres clinched their first playoff spot since 2006 by beating Seattle 7-4 in 11 innings.
The Padres have the NL's second-best record behind the NL West rival Los Angeles Dodgers. The Padres struck out 13 times and got just four hits.
Rookie manager Jayce Tingler said the Padres have been pressing a bit offensively recently, and it definitely showed Tuesday night.
"I was hoping tonight we would relax a little bit and kind of settle in to some more at-bats," Tingler said. "We did that certainly early; at end of day, Canning just did a really good job of mixing his pitches. The strikeouts stacked up on us. Some of that was he had a really good pitch arsenal tonight that got us a little bit out of whack."
The Angels remain mathematically in the race for the second wild card and for second place in the AL West.
Both of Stassi's homers were off Zach Davies (7-4). In the first inning, he hit a two-out shot an estimated 436 feet out to the bullpens in left-center. In the sixth, he hit a two-run moonshot to what is normally a beer deck in right-center for a 3-1 lead. He has seven this season.
It was the first career multi-homer game for the catcher.
"I've known I've had it in the tank. Happy to contribute to a win and focused on tomorrow, ready to hopefully get another one," Stassi said.
"I think everybody calls him The Babe' around here now," Canning said. "He was awesome tonight. It's been since last season since we worked together. It was fun, on the same page."
Said Stassi with a laugh: "I've heard it."
Canning (2-3) held San Diego to one run and two hits while walking five. Four of Canning's walks came early as he loaded the bases with no outs twice in the first three innings and escaped by allowing just one run.
"I felt good. I don't know why. I just felt good," Canning said.
"I feel they're one of those teams that tries to think along with me. I feel when I'm going well I'm able to usually be one step ahead. Kind of keep mixing things up. I pretty much threw everything had at them. A lot of curveballs, some changeups in there later once they started coming around and obviously fastball command was definitely better tonight -- besides the five walks. That opened things up and kept them honest."
Eric Hosmer, whose grand slam on Aug. 20 made the Padres the first team to hit a slam in four straight games, came up with the bases loaded and no outs in the first and hit a sacrifice fly. Fernando Tatis Jr. was thrown out trying to steal third and Tommy Pham struck out.
The Padres loaded the bases with no outs in the third and Manny Machado, who hit the third grand slam in the Padres' record streak, hit into a 1-2-3 double play and Hosmer took a called third strike.
Canning ended the fifth by striking out Tatis on a curveball.
Tatis slapped his bat in frustration.
"Tatis is who he is for a reason. He's an awesome player to watch," Canning said. "For me to throw that pitch, kind of broke out my old curveball there. To get that reaction, it felt good for sure."
Davies allowed three runs and seven hits in six innings, struck out five and walked three.
Angels: Four-time Gold Glove-winning SS Andrelton Simmons opted out of the remainder of the season. "At this time, I feel this is the best decision for me and my family," Simmons said in a statement. He will be eligible for free agency this winter.
Padres: LHP Matt Strahm (inflamed right knee) was activated from the 10-day injured list. To make room on the active roster, LHP Joey Lucchesi was optioned to the alternate training site.
Angels: RHP Jaime Barria (1-0, 3.26 ERA) is scheduled to start the series finale Wednesday afternoon. Earned the win in only other career appearance vs. Padres, at Petco Park on Aug. 14, 2018.
Padres: RHP Mike Clevinger (3-2, 3.10) is scheduled to start after being pushed back from Friday due to a sore biceps. It will be his fourth start since being acquired in a blockbuster trade with Cleveland on Aug. 31.
More AP MLB coverage: https://apnews.com/MLB
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