κυβερνήτης

What Jane Fonda’s workout tapes, Norbert Wiener’s wartime math, and your go-to-market motion all have in common, and why none of them work without a loop that closes.
Every founder is running a system they can’t name. It has an input, an output, and if it’s healthy a loop that checks the two against each other and corrects course. Most people call this “paying attention.” The Greeks had a tighter word: κυβερνήτης, the person steering the ship. It survives almost unchanged in English as governor, and more indirectly as cybernetics which the field Norbert Wiener founded to describe exactly this: systems that stay on course by measuring their own drift and correcting it.

You've felt this mechanism somewhere unlikely. Jane Fonda's aerobics tapes, decades before anyone in a gym said “cybernetics” out loud, were built entirely around feedback: check your heart rate, check the mirror, adjust the pace. Nobody got fitter by picking a plan on January 1st and running it unmonitored for a year. Fitness, the physical kind, only improves when you keep closing the loop between what you're doing and what's actually happening to your body. Building a B2B SaaS product and taking it to market is not meaningfully different. The fitness of a product to its market, and the motion built to sell it, are combined systems that need the same thing: orchestration through feedback, not a plan executed on faith. Hope is not a strategy.

The word before the theory

A steersman doesn't sail by the plan he wrote before leaving harbor. He sails by constant correction: checking the heading, the drift, adjust the tiller, and repeat. The plan told him where to go. It never told him how to get there in a real sea with real wind, tides and currents. Most founders run product and GTM strategy the other way around: write the plan, execute the plan, treat any deviation as an execution problem to fix with more effort rather than a signal to read. That's sailing with the tiller lashed.

Product-Market Fit (PMF) and Go-To-Market Fit are the two rudders on this ship, and conflating them is one of the more common reasons B2B SaaS companies scale prematurely. Or not at all.

Two different questions

PMF asks: does the product solve a real problem well enough that customers want it, use it, and stick around? Signals include strong retention and low churn, organic pull, referrals, inbound demand, usage depth, and willingness to pay at a reasonable price. PMF is about the product-customer relationship. It says nothing about how efficiently you can acquire new customers or expand them.

GTM Fit asks: do you have a repeatable, efficient way to acquire those customers at scale? Signals include a defined ICP, a sales motion (PLG, sales-led, channel) that reliably converts, predictable CAC payback, and reps or campaigns hitting quota consistently across multiple people, not just one founder closing deals through a personal network.

The key distinction: you can have PMF without GTM Fit. The product delights a niche of customers who find you, but you have no repeatable way to find more of them, which is common right after a great launch, pre-Series A. You can also have GTM motion without real PMF: a strong sales team can force early revenue through hustle even when the product doesn't retain well, which shows up later as churn, or what's politely called “ICP drift.”

Reading your own gauges

PMF is typically validated through retention curves and qualitative customer signal, which is why you measure Net Revenue Retention (NRR), Net Promotor Score (NPS), and customer health continuously rather than annually. Always ask (and track in the CRM) why customers chose you over the competition, and always log the features sales says are missing, every cycle, not just the escalated ones. Run NPS surveys at least twice a year. And no, “we know how our top customers generating 80% of revenue feel about the product” does not count as data. If it isn't substantiated, it isn't true. It's a story you're telling yourself.

GTM Fit is validated through unit economics like CAC, CAC payback period, magic number and whether the motion works with average reps, not just top performers, and if reps are needed at all. Aligning the motion to ACV band matters too: a motion tuned for a €10K deal will not survive contact with a €150K enterprise pursuit, and vice versa. (The Great GTM Dictator)

A useful heuristic: PMF is “will they stay.” GTM Fit is “can we affordably and repeatably get more of them.” Companies usually re-earn GTM Fit at every stage: an SMB motion doesn't transfer to enterprise , even after PMF is established, because ICP and buying process shift with segment. That drift is exactly what a governor exists to correct, if you've built one.

Cybernetics in 90 seconds

Here's Wiener's own diagram: the one that put a name on what Fonda's trainers, and every competent ship's captain, already knew instinctively.

Applying Product Market Fit onto the closed-loop system reads as follows:

Note on the loop. This is a negative feedback loop, meaning it's self-correcting only if the loop actually closes. If the Feedback Elements aren't built (no instrumentation) or the Controller ignores the Error Signal (data collected but not acted on) the system is effectively running open-loop. Output will drift regardless of how good the Input was. A founder with excellent product instincts and no dashboard is still, mechanically, sailing with the tiller lashed.

Same diagram, applied to the sales and marketing motion rather than the product itself.

Note on the cascade. The Plant differs between the two loops. PMF's plant is the customer base reacting to the product. GTM's plant is the prospect and pipeline population reacting to the sales and marketing motion. That makes GTM Fit a cascaded loop, sitting downstream of PMF. If the PMF loop hasn't converged (retention hasn't stabilized) churn will keep corrupting the GTM loop's output even when the GTM motion is well-tuned. That misleadingly reads as a GTM problem: bad reps, bad messaging. The real, uncorrected error is upstream, in the loop nobody's watching.

So what should you do?

You don't need a new operating model. You need three habits, run consistently enough that they stop feeling optional.

1. Track the right stuff, on a cadence, not a whim. Retention curves, NRR, NPS, customer health, CAC payback: these are gauges, not report-card metrics for the board deck. A gauge you check twice a year isn't a gauge. It's a rumor.

2. Build the feedback loop before the crisis, not during it. Instrumentation you wish you'd had six months ago is instrumentation you should build today. Analytics, churn interviews, win-loss analysis, rep scorecards because these have to exist before the Error Signal shows up, or you'll be diagnosing blind.

3. Act on the error signal quickly, and be honest about which loop it's in. Data collected but ignored is functionally identical to no data at all. And before you fix anything, check whether the problem you're seeing in GTM is actually a GTM problem or PMF drift wearing a GTM costume.

Κυβερνήτης didn't survive three thousand years and two etymological journeys: into governor, into cybernetics because steering is glamorous. It survived because every system that stays on course, a ship, a body, a go-to-market motion, does it the same way: measure the drift, correct the heading, and do it again tomorrow. Wiener wrote the math. Fonda ran the tape. Your job as GTM operator is just to close the loop.

Page updated

Google Sites

Report abuse