OAKLAND -- Chris Bassitt looks to be evolving into a reliable option for the A’s every fifth day, but he continues to be a victim of low run support.

Bassitt has allowed three earned runs or fewer in each of his four starts since getting called up to replace the injured Marco Estrada in the starting rotation, yet the A’s are now 1-3 in his outings after their 3-0 loss to the Reds on Thursday afternoon.

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“He’s been on fire,” A’s shortstop Marcus Semien said. “We just didn’t score for him. I looked up in the eighth and he was only at about 85 pitches. That’s all you can ask for.”

The key to Bassitt’s success this year has been his ability to keep hitters off balance with an impressive variation in pitch speeds. He entered the day with a fastball averaging 93.4 mph, which is a nice complement to his slow curveball that averages 69.4 mph. Utilizing his full arsenal of pitches against the Reds, which also includes a cutter, he turned in his longest outing of the season and racked up a season-high nine strikeouts over 7 2/3 innings of work.

Rising through the Minor Leagues as a power pitcher, Bassitt was forced to change up his style after Tommy John surgery in 2016 lowered the velocity on his fastball to around 88-90 mph. As is the case with most young pitchers, Bassitt struggled to adjust to the lowered velocity, but eventually figured out how to get batters out with better movement on his sinker and cutter.

Now that the velocity on his fastball is back, Bassitt has the best of both worlds, and it’s showing with a 2.55 ERA through four starts.

“I learned to pitch. When you’re throwing 89-91, you have to learn to pitch without a really good fastball,” Bassitt said. “The fastball came back and I was able to learn from that, and it made life easier.”

Bassitt allowed three runs on seven hits and a walk, but really only made two costly mistakes on the day, surrendering home runs to Derek Dietrich and Eugenio Suarez.

“I feel like I’ve made four or five mistakes the last couple of outings, and they’ve all been home runs,” Bassitt said. “It’s frustrating, but at the same time, you just tip your cap. They’ve been to good hitters.”

Power outage

The A’s relied heavily on their ability to mash home runs with the best of them in their run to the 2018 playoffs, finishing with 227, third-most in the Majors. They’ve hit 48 home runs in '19, good for 13th in the Majors, but they’ve homered only 16 times since April 12, the least in the American League over that stretch.

They recorded six hits on Thursday and did not have a base runner get past second base until the ninth.

“No doubt,” A’s manager Bob Melvin said when asked if there is concern over the recent lack of power. “It’s been a significant period where normally we’re able to spread it out around the lineup, even down at the bottom. It’s just not happening right now.

“We’ll have some good games, but more bad than good right now. A couple of good and hopefully we start swinging the bats like we’re capable of.”

Rotation coming around

The A’s starting rotation has been the subject of criticism over the season for its inability to consistently go deep into outings, but all three starters in the three-game series against the Reds managed to complete at least six innings. Mike Fiers tossed the second no-hitter of his career on Tuesday.

Bassitt’s long outing on Thursday allowed Melvin to limit the use of his bullpen, which was coming off a night in which it worked seven innings of a 13-inning victory.

“We’re pitching better,” Melvin said. “Not getting our timing right as far as offensively and on the pitching end, but it allows us not to have to use a bullpen that was used quite a bit last night. Now that starters are going deeper in games, it gives them a little bit of a break. Down the road, we should benefit from that.”

Update on Davis

Held out of the starting lineup on Thursday due to lingering issues from a left hip contusion, Melvin said he hopes slugger Khris Davis will be able to return on Friday when the A’s open a three-game series with the Indians.

“We tried to stay away from him today for a full day,” Melvin said. “He’ll hit in the cage and take batting practice tomorrow and we’ll see where we are at.”