PHILADELPHIA. Penn. — Spencer Howard became the 19th former Cal Poly baseball player to play in the Major Leagues on Sunday.

In the second game of a doubleheader at Citizens Bank Park, Howard pitched the first 4 2/3 innings, allowing four runs — a two-run home runs by Freddie Freeman, a solo shot by Ronald Acuna and an RBI double by Travis d’Arnaud — on seven hits. He walked one batter and struck out four.

The Templeton High School graduate left the game after notching his fourth strikeout, the Phillies trailing the Atlanta Braves 4-0. Atlanta went on to complete a sweep of the twinbill with an 8-0 victory.

Howard is the 10th Mustang under head coach Larry Lee to play in the Majors. Cal Poly had nine Major Leaguers in the first 97 years of the baseball program (1905-2002, did not play in 1944 due to World War II) and, with Howard’s call-up Sunday morning, Lee surpassed that total in 18 seasons at the helm.

Two of Howard’s strikeout victims were recorded by Marcell Ozuna, who spiked his bat into the ground and snapped the handle in the fifth inning, frustrated that he could not connect on Howard’s slider.

Howard is baseball’s No. 36 prospect, according to MLB Pipeline, because he has an electric fastball and three impressive offspeed pitches, wrote Todd Zolecki of MLB.com. Howard showed flashes of his potential Sunday, but he also showed there is room for improvement.

The Braves swung aggressively. Howard faced 22 hitters. They swung at the first pitch 13 times, perhaps figuring that Howard would try to get ahead in the count with a first-pitch fastball. He threw 12 first-pitch fastballs.

Howard threw six sliders and got four swings and misses on them, indicating the Braves were looking fastball.

His fastball averaged 93.5 mph and maxed out at 95.5. Surprisingly, Howard didn’t get a single swing-and-miss on the 41 fastballs he threw, reports Corey Seldman of NBCSports.com.

Bryce Harper, who had pined for Howard to join the Phillies’ rotation, said to NBCSports.com about his new teammate:

“I’m excited for him. This is where it starts. It’s not minor league ball anymore, it starts now. Excited to get him up here and get him acclimated to this team and how we go about it. He’s a great competitor. He’s got plus-plus stuff. Phillies fans should be very excited to see what Spence does.

“He just needs to be Spence,” Harper added. “That’s the biggest thing when guys get up here, change this or change that, people want to see you do this or do that. But my biggest thing is when guys get up here, I want them to be able to enjoy themselves, take in the moment and really know they have the stuff to be here. I just want him to enjoy the moment.”

After the game, Howard provided a report card of his performance.

“I was hoping for a complete-game shutout. That’s what everybody would dream about,” Howard said. “But just being able to compete at the highest level, a dream come true.

“I wouldn’t say I felt sharp,” Howard added, “just a little out of sync with my mechanics. I left a lot of balls over the plate and mistakes get hit in the big leagues.”

Phillies manager Joe Girardi has not yet indicated when Howard will start again. .

Howard did not know for certain until Friday night that he would be making his Major League debut Sunday when he got a call from minor-league director Josh Bonifay.

“It seemed like I was the last person to know in the United States that I was going to pitch today,” said Howard, whose family watched on television in Templeton. “But a bunch of my buddies texted me. Friends and family were really excited, so I kind of got that feeling. I tried to stay as even-keeled as possible and not let the moment get too big.”

Howard signed with the Phillies for a $1.15 million bonus after he was selected in the second round, the 45th overall pick, in 2017. Named a second-team All-American by Collegiate Baseball Newspaper with an 8-1 record, Howard finished second in the Big West with his 2.05 ERA and his eight wins also were No. 2. Howard struck out 97 batters, third in the conference, over 87 2/3 innings, averaging nearly 10 strikeouts per nine-inning game.

Nationally, Howard was No. 23 in ERA, No. 71 in WHiP (1.08), No. 49 in victories, No. 58 in strikeouts and No. 91 in strikeouts per nine innings.

A first-team All-Big West selection in 2017 and a graduate of Templeton High School, Howard won his last five starts and became the first Mustang starter in five years to finish the season with just one loss. He earned the team’s Mike Krukow Outstanding Pitcher award.

A redshirt in 2015, Howard was primarily a reliever as a redshirt freshman in 2016 and posted a 3-1 record and 2.95 ERA and one save. He struck out 39 over 36 2/3 innings.

A 2014 graduate of Templeton High School, Howard was an outfielder and pitcher on the Eagles’ baseball team. He hit .306 and compiled a 7-3 record and 2.20 ERA as a senior, earning San Luis Obispo County Player of the Year and Los Padres League most valuable player honors. He struck out 87 batters in 66 2/3 innings.

• Another former Mustang, Mark Mathias, extended his MLB career-opening hitting streak to four games with a single in the sixth inning of Milwaukee’s 9-3 victory over Cincinnati at Miller Park.

Starting in right field for the third time after a start in left field, Mathias went 1-for-4 in Sunday’s game and is now 5-for-15 (.333) with two runs scored, two RBIs and a stolen base in his Major League career. His single Sunday sparked a six-run Brewers rally.