LAS VEGAS — Sunday’s race with both the tapered spacer and aero ducts as part of the 2019 rules package for NASCAR’s top series was as unpredictable as anticipated at Las Vegas Motor Speedway. But the setup’s performance was also noteworthy for how several of those pre-race forecasts didn’t take.

At day’s end, Steve O’Donnell, NASCAR Executive Vice President and Chief Racing Development Officer, said the package won’t be judged by Sunday’s Pennzoil 400 alone. O’Donnell said he saw positive indicators at the 1.5-mile track, but the package will continue to be a work in progress.

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“We’ve said from the beginning that this is going to be a season that we’re going to analyze,” O’Donnell said. “We’re not going to go every race and say, ‘Was that a good race, was that not?’ I know fans do that, but for us, directionally are you improving upon where you wanted to be. And if you look at last year versus this year, I would say we are.

“Was it tremendous improvement? Probably not. But again as a fan, you want to see lead changes. We saw that today, and I think if you would’ve looked in the past with no cautions, we would’ve seen someone check out all race long and we wouldn’t have seen a lead change.”

Sunday’s race was an extension of the previous weekend’s event at another intermediate track in Atlanta Motor Speedway, with increased downforce and a reduction in horsepower. The Las Vegas event went a step further with the addition of aerodynamic ducts to produce a larger wake from a leading car to trailing cars.

An organizational test, qualifying and practice fed a variety of pre-race predictions, but the package’s predicted resemblance to restrictor-plate-style racing on a smaller-scale track didn’t quite pan out, with only glimpses of pack-style competition during restarts. Prophecies of mass destruction and multi-car crashes faded with a caution-free race, save for the two stage breaks. And the prognosis for an underdog surprise also fizzled, with an array of heavyweights making a clean sweep of the top five.

“You go back even before the race — and I think even some of the media and it probably came from the garage: ‘We’re going to wreck the entire field, this isn’t going to be a race.’ Didn’t happen,” O’Donnell said. “Some said NASCAR’s goal is pack racing. Not the case. Our goal was to bring cars closer together, have more lead changes, but again, (I) was surprised. I think if we had more green-flag restarts, I think you probably would’ve seen one or two wrecks, but we’ll see. It’s early, again. I’d rather err on the side of not wrecking cars and having some lead changes versus having that happen through accidents.”

O’Donnell said the 400-miler almost played out as a tale of two races, with a tamer Stage 1 as a prelude to slightly more intense competition in the next two portions. The race featured 19 lead changes, a figure that was down from the 23 that occurred in sweltering conditions last September, but the highest for the annual March event at Vegas since 2016 (see chart below for more).

Not surprisingly, Joey Logano savored how the package played out from his premium perch in Victory Lane. Other drivers expressed difficulty with passing ability, saying teams are still trying to establish a better understanding of how the package will unfold. Sunday, drivers were still trying to digest the early impacts.

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“The package was insane on restarts,” said Kurt Busch, who wound up fifth. “The adrenaline and the activity, everyone racing harder, with three-wide. I mean, you didn’t know where cars were going to come from, and then yes, we did get strung out, but handling comes back into play. You’ve got to make your car handle and we had just enough handle on our car to get a top five today.”

The full package will return in two weeks at Auto Club Speedway for the Monster Energy Series’ first trip to a 2-mile track this season. Though O’Donnell said there was still work to be done, he was pressed post-race for what he wanted to see from the package’s performance.

“I think it’s not really up to me, right? It’s the fans,” O’Donnell said. “You want higher ratings and you want more butts in seats ultimately. You want rivalries out there and drivers getting after it, and I think what happens in that situation is you have more passes for the lead and you have cars closer together, so I think we’re on the march to do that. I think we saw some of that today, but we can continue to improve on it.”