Aaron Nola spent the final day of the season’s first half in the back seat of a private car, listening during a five-hour drive to the radio broadcast of a game he was supposed to pitch.

“It sucked,” said Nola, who was scratched from pitching earlier this month in Boston because he is unvaccinated against COVID-19 and came into contact with a teammate who had contracted the virus.

For Nola, it was a frustrating finish to a frustrating 15 weeks. He spent the previous three seasons as one of the National League’s premier pitchers, yet his ERA through 18 starts (4.53) is 12% worse than the league average.

He pitched a shutout in April, was inconsistent in May, lasted less than three innings in a June start, and was placed on the COVID-19 injured list hours before what was scheduled to be his final start of the first half.

The Phillies did not get what they expected from Nola during the first half, yet they will still be in striking distance of first place when he pitches Tuesday night at Yankee Stadium in his first start of the second half.

Their No. 1 starter has pitched at times like a middle-of-the-rotation arm, but the Phillies are two games above .500 for the first time in two months. And their route to October becomes much clearer if Nola can right his season.

“I can point to underlying statistics and say he hasn’t had the best luck,” pitching coach Caleb Cotham said. “I know luck is part of this game. He would even say he wants to pitch better, but I don’t think he’s pitched as bad as, say, his ERA says he has. If he just sticks with it and keeps working, we’ll look up at the end of the year, and he’ll have had a really, really nice season.”

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There is some truth to Nola’s bad luck as his batting average on balls in play (. 331) is at a career-high rate and 48 points higher than last season. Nola’s contact rate (73.3%) and average exit velocity (88.8 mph) are on par with his career-best numbers. But more hits are falling against Nola than ever before.

His xFIP — an advanced stat similar to ERA but accounts only for events a pitcher can control such as strikeouts, walks, hit by pitches, and fly balls — is a half run higher than last season but close to where it was in 2018, when Nola was a Cy Young finalist. A low xFIP is usually an indicator that a low ERA could be coming once everything evens out.

But Nola’s ground-ball rate (40%) is at a career low, and his fly-ball rate (38.5%) is at a career high. Nola, like most pitchers, is at his best when he’s racking up strikeouts and keeping the ball on the ground. Nola’s ground-ball rate from 2018-2020 (50.1%) is the seventh-best among all starters. He’s still generating strikeouts (11.19 strikeouts per nine innings), but his struggles to get ground balls have been hard to overcome.

Nola battled in the first half with the command of his fastball, a pitch he usually controls with great precision. Hitters are batting .261 this season against the fastball with a .460 slugging percentage after batting .154 last season with a .365 slugging.

Nola is throwing his fastball just as much as previous seasons, but it has been less effective.

“There’s been some delivery changes in the last month,” Cotham said. “He did some homework. We did some homework, and we saw some things. I don’t think they were big things, but small things do create big things in the delivery. I can tell you that he’s in a great spot. It’s as good as I’ve seen him move, and it’s really similar to years past. I think it does flow through the delivery for him. If you feel good about the delivery and feel good about what you’re doing to deliver the ball, the ball is more apt to listen.”

Nola spent four days away from the team last week, keeping his arm loose by throwing against a fence at a city park. He said he felt fine on Friday when he rejoined the team in South Philly, and his time on the COVID-19 injured list cost him just one start.

He has pitched his best over his career in July and August as he has a 2.84 ERA in 52 starts over those two months. The Louisiana native likes to pitch when the heat rises, and it will be near 90 degrees when he throws his first pitch Tuesday night.

He won’t be listening on the radio. Instead, he’ll be trying to right his season after a frustrating first half. And if Nola does, it will allow the Phillies a clearer path to the postseason for the first time in a decade.

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“There’s context clues,” Cotham said when asked if he can tell if the low-key Nola is frustrated. “But that’s him. Any pitcher who has pitched as well as he has for as long as he has, you have to have that demeanor. He’s very even-keeled. You have to search for like, ‘Is he frustrated?’ I know he wants to be the best. I think that’s what I’ll hang my hat on, and I’ll keep working for him and with him. When you have that mindset that you don’t get too frustrated, you don’t get too high or too low, it will come.”