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What matters at Phoenix: Pit stops, restarts will shape championship race

Dale Jarrett joins Corey Parson and Drew Dinsick to break down the NASCAR Cup Series Championship at Phoenix Raceway.

What matters in today’s Cup race (3 p.m. ET on NBC and Peacock), and how will pit stops and restarts shape the championship picture? Let’s dive into the relevant analytics and trends at Phoenix Raceway:

All can be lost on a pit stop (or two, or three)

In 2020, Brad Keselowski and Jeremy Bullins brought an undefeated chassis to the season finale in Phoenix. They figured it was their best vessel for a shot at winning the series championship.

Their hunch was correct. The car ranked as the fastest of the race, based on timing and scoring data. But that wasn’t good enough. They finished second in large part because of their pit crew’s woeful effort on the day.

Keselowski’s over-the-wall crew cost him 13 positions on caution-flag pit stops. His final turn as the race’s leader ended after lap 195 — on pit road, not on the racetrack. His above-par passing out of those internally inflicted deficits still couldn’t overcome Chase Elliott, the eventual winner and champion.

This year’s crop of championship contenders fare among the best position-getters in a variety of statistical measures; however, Keselowski, himself a brilliant short-run performer, proved that track position near the front in this particular race is elusive. It’s a lesson that bears learning: Even the most adept climbers can’t reach the surface if they’re buried too deep.

In what is slated to be the final race of the five lug-nut era, it’s fitting that the championship could be decided — or most likely lost — on a pit stop. At first blush, it appears all four Championship 4 teams are in good shape. They each rank within the top five for median four-tire box time across the last nine playoff races:


The four pit crews are effectively close, separated by one-tenth of a second with Kyle Larson’s team enjoying the advantage. The remaining three are within, no kidding, one-thousandth of a second. One long pit stop, either by virtue of a mistake or adjustments meant to improve handling, will be costly, because it’s most likely that other competitors won’t err badly enough for a position to change hands.

And it’s not just errors — simply not having stops on par with the opposition will keep good cars out of the lead. Case in point, Denny Hamlin had the fastest car in the spring race at Phoenix, per its median lap time ranking, but 31 of his 33 laps led came before or during the competition caution. After Joey Logano passed him shortly after a restart, Hamlin was stymied as Logano’s pit crew reeled off three sub-13-second stops compared to one for Hamlin’s crew.

Despite having a faster car, Hamlin couldn’t corral Logano. Clean air, an advantage frequently defended on pit road, dictated the day’s green-flag runs.

Restarts will set the tone for all that comes after

Immediately following each caution-flag pit stop is a restart. And double-file restarts, which set the tone for subsequent green-flag runs, make for quite the show at Phoenix.

NASCAR, of course, has ensured this to be the case. For the spring race, the PJ1 traction compound was applied to the outer groove. The thinking was that it’d make the high line more effective and, possibly, the desired restart lane.

But that wasn’t the case. Within the top 14, drivers in the inside line defended position at a higher rate — 73.2% compared to the outside’s 46.4% clip. Those restarting from the inside groove have more width, thanks to the apron adjacent to the dogleg, something Keselowski demonstrated early in the race to nearly a heart-stopping degree:


More measured approaches also proved successful. Logano selected the inside groove as the leader three times — on laps 84, 99 and 200 — and retained the lead with each attempt. Up until the final restart on Lap 288, the car restarting from the inside of the front row had only been passed once, and the passer emerged from the inside of the second row, not the outside of the front row.

That’s what made Logano’s loss of the lead hard to swallow. Martin Truex Jr., from the outside of the front row, took advantage of the remaining grip from the traction compound to hold onto his car well enough in the center of the corner to swipe the lead:


It was a move of the kamikaze variety, to be sure, but involved some calculation. Truex’s execution was counter to those who previously utilized the outside groove. Instead of trying to out-duel Logano in the dogleg, he got back into the throttle on the dogleg’s exit before Logano did and stayed on the throttle longer going into the next corner.

“He drove in deep. I drove in deeper,” Truex said.

An elite restarter — he ranks second in position retention rate on restarts across all tracks — Truex was aware of his limitations, saddled with a restart spot he didn’t prefer.

“If I was the leader,” he said, “I probably would have chose the bottom as well.”

In lieu of PJ1, resin has been applied to the same high line around Phoenix for today’s race. Whether a driver is able to securely hold on to his car in the manner Truex did is unclear; what is a likelihood is the strength of the inside line, especially among leaders. It’s an inherent advantage to lead the race, but for some, it’s practically a requirement in advance of each restart:


Three of the Championship 4 — Truex, Larson and Elliott — are better restarters from the front row than they are in traffic. Truex and Larson, in particular, are downright deadly when seeing clean air at the start of a run, both retaining at least 85% of such attempts in playoff races.

But their rates fare worse when clean air is absent. Larson defends his restarting spot far less frequently, by over 20 percentage points. Truex’s gap is 17 percentage points. It’d behoove their teams to keep them at or near the front, helping to build a relatively impenetrable firewall on short runs.

Hamlin represents the outlier. In an odd twist, he’s been less successful at retaining front-row restarting spots, doing so at a 59.3% rate, but his defense when mired between the second and seventh rows is outstanding by comparison. In playoff races, he’s maintained his running position on 32 of 36 attempts. This suggests he’s the driver most impervious to further drops in the running order when he can’t depend on clean air. But good defense doesn’t necessarily translate to offense.

That’s why we’re likely to see title contenders driving in “deeper” as Truex succinctly put it. Ideal track position at Phoenix is elusive, at times fleeting, and the opportunities for gains are few and far between. Caution flags, which prompt pit cycles and restarts will create the very moments of vulnerability that have affected past races at the 1-mile facility.

Today, those moments will determine which of the four combatants hoists a championship trophy.