CINCINNATI -- Left-hander Patrick Sandoval was impressive in his Major League debut, but he wasn’t helped by the decision to use an opener, as Taylor Cole gave up five runs in the first inning before Sandoval entered the game.

Sandoval, though, showed promise, allowing two runs on three hits over five-plus innings with eight strikeouts in a 7-4 loss to the Reds in the series opener at Great American Ball Park on Monday. It was the fifth straight loss for the Angels, who fell to 56-58, but Sandoval’s strong showing at least provides some optimism going forward.

• Box score

"It was an excellent first start,” Angels manager Brad Ausmus said. “He should be happy with the way he pitched. The results were good. He can't do anything about the score before he comes in. He was excellent."

Sandoval, ranked as the club’s No. 11 prospect by MLB Pipeline, showed better velocity than expected, as his four-seam fastball averaged 93 mph and maxed out at 96 mph. The 22-year-old’s changeup was his most effective offspeed pitch, generating 11 of the 17 swings and misses he induced.

Sandoval, who grew up near Anaheim in Mission Viejo, said the increased velocity was because he was amped up in his first inning, but that his fastball generally ranges from 92-94 mph. He had 11 family members at the game and said being able to pitch for his hometown team led to the adrenaline early in his outing.

“Felt the juices flowing a little more than usual,” Sandoval said. “But I think I settled in pretty well and I attacked the game plan the way we designed it. [The changeup] is just a big pitch for me in general. When it’s on, I feel like I can go to it whenever I want. That’s when I have the most success."

With the Angels already in a 5-0 hole, Sandoval gave up a run in his first inning after walking Jesse Winker to open the second. Winker eventually came around to score on a wild pitch from Sandoval with one out.

But Sandoval cruised from there, retiring 12 of the next 14 batters he faced until running into trouble in the seventh. He walked Phillip Ervin to open the frame and gave up a single to Joey Votto before being removed for right-hander Luis Garcia. Garcia allowed an inherited run to score on a wild pitch of his own with two outs.

“As he went on, the breaking ball got better, the fastball command got better and the changeup was excellent," Ausmus said of Sandoval.

Sandoval wasn't particularly efficient, needing 96 pitches to record 15 outs, but he showed that he has the stuff to stick in the rotation going forward. The Angels had high hopes for Sandoval coming into the season, and while he struggled at Triple-A in the high altitude in Salt Lake City, he still possesses swing-and-miss stuff. He was acquired from Houston for catcher Martin Maldonado, and he’s considered one of the organization’s top young pitching talents, along with Griffin Canning, Jose Suarez, Jaime Barria and prospect Luis Madero.

"It’s a different ballgame down there in Triple-A," Sandoval said. "Hearing all the coaches tell me that my stuff plays up here and seeing it happen, it’s a good feeling."

Trout hits 37th homer

Sandoval didn’t receive much help from the offense, as the Angels struck out a season-high 13 times over seven innings against right-hander Luis Castillo. But Mike Trout connected on his 37th homer of the season in the sixth inning, keeping him neck and neck with the Brewers' Christian Yelich (who homered twice Monday and is at 39) and the Dodgers’ Cody Bellinger (who homered once Monday and is also at 37). The homer traveled a projected 442 feet into the second deck in left and had an exit velocity of 110.3 mph, per Statcast.