McLaughlin began the weekend with the fastest time in Practice 1 but suffered a high-speed crash in the subsequent Practice 2.
The New Zealander dropped his right-side tyres onto the grass entering Turn 1 and tipped the car into a 180-degree spin.
McLaughlin went backwards into the tyre wall and part-way through the catch fence.
He made it out for qualifying and ended up 14th before falling to 16th in the 90-lap race.
“Tough day for us in the Odyssey Battery Chevy,” said McLaughlin.
“We didn’t quite have the pace on the blacks (hard compound tyre).
Secure your spot today.
“It was a little bit better on the red (soft compound) tyre, but ultimately just didn’t have the pace in general.
“Just frustrating because there was a lot of promise.
“I felt like we were pretty good as the tracks sort of came up, it was it got hotter and hotter.
“So, we’ve got a little bit of work to do to figure out what went on this weekend.
“Obviously, my crash didn’t help. But, you know, just gonna move on.
“We’ve got a lot of work to do on my end.”
While McLaughlin went backwards, Will Power was IndyCar’s biggest mover at Barber, climbing an impressive 11 places.
The Andretti Global driver came up short of the top 10 in his recovery mission, which began from 23rd on the grid and ended with the #26 finishing 11th.
It was a big bounce back for the Australia, who crashed a day earlier in the first leg of qualifying due to a brake failure.
“Today was about as good as we could do,” said Power.
“We had very good execution on strategy and a bit of a slow stop at the end.
“I think we had the potential for 10th, but we got close to our full potential today.
“The TWG AI Honda was great.”
Despite his qualifying crash, Power said he thought he could win the race.
He reaffirmed his view that he is capable of winning this year.
Teammate Kyle Kirkwood was a win to his name this season at Arlington, while Power was third in that race.
“Once again, we have the ability to win races for sure,” said Power.
“We’ve got a very good team here, so looking forward to the rest of the season.”
IndyCar returns with the Grand Prix of Long Beach on April 19.
Palou perfect at Barber as pit stop problem thwarts Lundgaard
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