Measuring the Pareto of Customer Success Beyond NRR

Customer Success teams have historically relied on a single metric to evaluate the health of their business:

Net Revenue Retention (NRR).

NRR is useful.

It tells you whether revenue from existing customers is growing.

But NRR alone cannot explain why growth happens, whether that growth is profitable, or whether the customer portfolio is structurally healthy.

A company can report a healthy NRR while:

• spending too much to support customers

• expanding the wrong accounts

• carrying large numbers of low-margin customers

• relying heavily on a small set of accounts for growth

To understand the true health of the customer portfolio, Customer Success leaders must measure the Pareto structure behind NRR.

This requires looking at a set of additional metrics:

• Net Revenue Retention (NRR)

• Cost-to-Serve (CTS)

• Gross Margin

• Expansion Efficiency (EE)

• Pareto Health Score (PHS)

Together these metrics explain which customers drive value and which ones consume it.

1. Net Revenue Retention (NRR)

What it measures

NRR measures how revenue from existing customers changes over time.

It accounts for:

• Renewals

• Expansion

• Churn

• Contraction

NRR answers a simple question:

Is the customer base growing or shrinking?

Formula

NRR =
(Starting Revenue + Expansion − Churn − Contraction)
÷
Starting Revenue

Example — Strong Contributor

Starting revenue:

$100K

Expansion:

+$40K

Churn / contraction:

$0

Calculation:

NRR = (100 + 40) ÷ 100
NRR = 140%

Interpretation:

This customer generates strong growth.

Example — Weak Contributor

Starting revenue:

$100K

Expansion:

$0

Contraction:

-$20K

Calculation:

NRR = (100 − 20) ÷ 100
NRR = 80%

Interpretation:

Revenue from this customer is declining.

Why NRR is not enough

NRR shows revenue movement, but it does not show:

• How expensive the customer is to support • Whether expansion was efficient • Whether the account contributes to margin

This is where additional metrics become essential.

2. Cost-to-Serve (CTS)

What it measures

Cost-to-Serve represents the total cost required to support a customer annually.

It includes costs such as:

• Customer Success team time • Support and technical assistance • Onboarding and implementation • Infrastructure or hosting • Professional services

CTS answers a critical question:

How expensive is this customer to maintain?

Formula

CTS = Total annual cost required to support a customer

Example — Strong Contributor

Customer revenue:

$500K

Support costs:

Customer Success time: $40K
Support engineering: $20K
Infrastructure: $15K

Total CTS:

$75K

Interpretation:

Supporting this customer costs $75K per year.

Example — Weak Contributor

Customer revenue:

$80K

Support costs:

Customer Success time: $40K
Support engineering: $30K
Infrastructure: $20K

Total CTS:

$90K

Interpretation:

This customer costs more to support than it generates in revenue.

3. Gross Margin

What it measures

Gross Margin measures the profitability of a customer after direct service costs.

It answers the question:

How much profit remains after supporting the customer?

Formula

Gross Margin =
(Revenue − Cost-to-Serve)
÷
Revenue

Example — Strong Contributor

Customer revenue:

$500K

Cost-to-Serve:

$75K

Calculation:

(500 − 75) ÷ 500
= 425 ÷ 500
= 85%

Interpretation:

This customer generates high profitability.

Example — Weak Contributor

Customer revenue:

$80K

Cost-to-Serve:

$90K

Calculation:

(80 − 90) ÷ 80
= −12.5%

Interpretation:

This customer generates negative margin.

Even if the account renews, it reduces profitability.

4. Expansion Efficiency (EE)

What it measures

Expansion Efficiency measures how efficiently Customer Success generates expansion revenue.

It evaluates the return on the resources invested in growing accounts.

EE answers the question:

How much profit do we generate for every dollar invested in expansion?

Formula

Expansion Efficiency =
(Expansion Revenue − Cost of Expansion)
÷
Cost of Expansion

Example — Strong Contributor

Expansion revenue:

$200K

Cost of expansion activities:

$50K

Calculation:

(200 − 50) ÷ 50
= 150 ÷ 50
= 3.0

Interpretation:

Every $1 invested in expansion generates $3 of profit.

This is highly efficient.

Example — Weak Contributor

Expansion revenue:

$60K

Cost of expansion activities:

$80K

Calculation:

(60 − 80) ÷ 80
= −0.25

Interpretation:

Expansion efforts lose money.

5. Pareto Health Score (PHS)

What it measures

The Pareto Health Score evaluates whether the customer portfolio is structurally balanced.

It analyzes the relationship between:

• Revenue concentration

• Expansion sources

• Cost discipline

• Portfolio management decisions

While NRR measures growth, PHS measures whether that growth is sustainable.

Formula (this is a Project Moneyball interpreation and recommendation)

PHS =
(Revenue Concentration × 30%)
+ (Expansion Contribution × 30%)
+ (Cost-to-Serve Discipline × 25%)
+ (Portfolio Action Discipline × 15%)

Each parameter is scored from 0 to 100, then weighted.

Example — Healthy Portfolio

Scores:

Revenue concentration = 70
Expansion contribution = 85
CTS discipline = 75
Portfolio action discipline = 80

Calculation:

(70 × 0.30) +
(85 × 0.30) +
(75 × 0.25) +
(80 × 0.15)

= 21 + 25.5 + 18.75 + 12
= 77.25

Interpretation:

The portfolio is healthy but still improving.

Example — Weak Portfolio

Scores:

Revenue concentration = 40
Expansion contribution = 50
CTS discipline = 35
Portfolio action discipline = 30

Calculation:

(40 × 0.30) +
(50 × 0.30) +
(35 × 0.25) +
(30 × 0.15)

= 12 + 15 + 8.75 + 4.5
= 40.25

Interpretation:

The portfolio is at risk.

Why Customer Success Must Measure the Pareto

When Customer Success relies only on NRR, the portfolio can hide structural issues.

For example:

• A few large accounts generate most expansion

• Many small accounts consume large amounts of service capacity

• Expansion effort becomes inefficient

• Profitability declines

By combining NRR with CTS, Gross Margin, Expansion Efficiency, and PHS, leaders can identify:

• Which customers generate value

• Which customers consume resources

• Which accounts should be scaled

• Which accounts require automation or restructuring

The Real Role of Customer Success Metrics

NRR measures revenue growth.

But the Pareto metrics measure something deeper:

the architecture of the customer portfolio.

And revenue architecture determines whether growth compounds or collapses under its own weight.

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Avner Baruch Founder & Author Project Moneyball