“The beauty of this is its simplicity. Once the plan gets too complex, everything can go wrong.” — Walter Sobchak, “The Big Lebowski”

The biggest questions in auto racing usually have simple answers.

The above quote from John Goodman’s way-too-complex Walter, from a stoner flick old enough to buy its own White Russian, serves as perfect meta commentary on the nature of analytics in sports (and, probably, the very writer you’re reading right now). In order to obtain simple answers to big questions, one must take complex routes in creating something easily understood.

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The question “When is a NASCAR driver’s peak?” often yields opinions, but opinions don’t answer the question. There is an answer out there, and it is factual.

To get to this answer, the careers of every driver active from 2002 through 2019 were logged, noted and, in some cases, extrapolated to full-season samples to home in on one number: PEER, or Production in Equal Equipment Rating, if you’re not into the whole brevity thing.

What is PEER?

PEER was created in 2010 and revealed to the public in 2012 by Motorsports Analytics. The rating considers a driver’s race result and handicaps team and equipment strength, using the GPS data available to manufacturers and teams in a proprietary formula, in an attempt to isolate his or her contribution.

• A positive PEER indicates a driver who regularly contributed to the result, even considering the strength of everything and everyone at his or her disposal.
• A zero PEER (0.000) indicates no contribution by the driver and a team/car with no expectations, most frequently seen with back-markers or start-and-park teams.
• A negative PEER indicates a driver whose mere presence behind the wheel made a good team less competitive; to wit, it appears teams have become smarter with their hiring decisions over the last decade. In 2019, just 6 percent of all drivers with six or more starts earned negative ratings, down from 19 percent in 2009.
• The average PEER among all drivers for an individual season often hovers around 1.000; the average in 2019 was 0.965.

With a PEER for every driver in each season across this time frame, we can find an average for each age and create an aging curve:

Whether a driver is “good” or “bad” is probably too broad of a question to be answered by the aging curve; however, we can easily identify whether a driver is above or below their age’s average by the whereabouts of his or her PEER in relation to the curve. Above the curve? Above average. Below the curve? Below average. See? Simple answers to simple questions found through complex means. Clear as mud.

How about we use the aging curve to answer a few pressing questions?

When is a NASCAR driver’s peak?

The age-39 season. It’s the apex of the curve, with ages 38 to 40 representing a prime period when the getting is good. To a man, this won’t always be exact — Mark Martin’s most productive age was 39, Dale Jarrett’s was 40 and Kevin Harvick’s was 42; The second-most productive seasons for Jimmie Johnson, Dale Earnhardt Jr., Martin Truex and Harvick came at 39 — but this appears to represent the most reliable, bountiful period of a career.

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Is Jimmie Johnson over the hill?

Yes. The 2020 season will be his age-44 effort. Our chart tells us that’s a clear decline phase for most drivers. His 1.278 PEER in 2019 is a big drop from his 3.972 of 2015 (his age-39 season). There’s nothing inherently wrong with him; this is just the way things tend to go.

But Kevin Harvick is the same age as Jimmie and he’s still really good. Why?

Some drivers age a little more gracefully than others, and in Harvick’s case, he’s aging like a fine wine surrounded by an organization with access to F1 technology and a crew chief (Rodney Childers) who can reliably produce the series’ fastest car around his driver’s abilities or lack thereof. But don’t get this twisted: Harvick’s production is in decline. His 3.347 PEER from 2019 (as a 43-year-old) is nearly a 0.800-point drop from his 4.139 at age 39.

Kyle Busch has yet to hit his prime. Can he win 200 Cup Series races?

It’s highly doubtful. In order to do this, he’d need to win every race over the next four years or 18 over the next eight or nine over the next 16.

Can Kyle Busch win 100 Cup Series races?

Sure. Including age 40, he has five years to climb toward or be at his production pinnacle. If he wins eight or nine times per season, he’s good to go. If he has a Harvick-like prime, and produces at a high clip through age 42, he’ll need to win a little more than six races per season. The latter scenario feels entirely possible.

Should we be worried about Chase Elliott, Erik Jones or William Byron, former top prospects who should be competing for wins and championships with good teams?

No. On average, drivers don’t break the 1.000 PEER barrier until age 24. Both Jones (who ranked eighth in 2019 with a 1.903 PEER) and Elliott (ninth with a 1.833) are 24 for the majority of 2020. Byron has two years to go. Considering ages 20 to 23 represent the production wilderness — these are college and/or first-time adult years for most — expectations should be kept in check. Let the young men figure out life. Evaluate them based on their age, and not in relation to older, currently elite drivers.

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If drivers are starting their Cup careers at a younger age, won’t the prime age come sooner?

Nope, because that’s not how this works. There are some aspects of biology and cognitive functioning you probably aren’t considering. For instance, a 2014 study by authors from Simon Fraser University in Burnaby, B.C., Canada, found reaction time begins to decline at age 24. Multiple studies suggest eyesight and the ability to perceive depth and peripheral vision, both paramount to driving race cars, begin to decline around age 40. It’s likely that in between those two ages, drivers are kept afloat with keen eyesight and accrued racing knowledge. Until LASIK surgery becomes a popular, legal performance enhancer making the peak age older, then the most likely scenario is the current prime period standing pat for the foreseeable future.

Analytics in any sport is a tool for evaluation, rooted in fact. For NASCAR, the knowledge of how drivers age allows many of the hard evaluation-related questions to crystallize into clear answers that we can then begin to complicate with nuance or personal preference.

But everything starts here, with the aging curve. It’s the rug really tying this whole room together.

(Top photo: Jonathan Ferrey / Getty Images)