Definition
The Hybrid Squad Efficiency Ratio (HSER) measures how effectively one human leader uses a team of AI agents to expand productive output. In simple terms, it shows how much more useful work a person gets done by managing agents than they could do alone.
Greg Kihlström introduces HSER in Marketing Operations 3.0 (De Gruyter Brill) as a way to make “the idea of managing multiple agents measurable.” The book is specific about where it fits: HSER is a driver metric that helps explain changes in Return on Agent (ROA). It isn’t a measure of economic value on its own. As the book puts it, “a team can show a strong efficiency ratio and still accelerate poor decisions.”
See also: Key Performance Indicator (KPI) · AI Agent · Human-in-the-Loop (HITL) · Total Cost of Ownership (TCO)
Why it matters for marketing
The book’s working unit for AI-driven marketing is the human-agent squad: one human lead overseeing roughly five specialized agents (the “1-to-5 model”). The book calls this “a practical unit of managed leverage.” HSER is how that leverage gets measured.
Without a metric like this, it’s hard to tell whether a squad is actually working. A marketing ops lead might oversee five agents and still spend most of the week fixing their mistakes, approving routine actions, and reconciling data. On paper the team looks automated. In practice, the person may be no more productive than before.
HSER also reflects a broader change in how marketing talent is evaluated. The book argues that people in hybrid roles should be “measured by managed leverage” rather than by the volume of work they personally touch. In the book’s model, the CFO’s seat on the CO2 Council uses HSER as its key metric, which shows it’s meant to inform resource allocation, not just team reporting.
How to calculate HSER
The book defines what HSER measures but doesn’t prescribe a formula. A practical way to calculate it:
HSER = Qualified output of the hybrid squad ÷ Baseline output of the human lead working without agents
Both numbers should cover the same period and the same type of work.
- Qualified output is completed work that met quality and guardrail standards. Exclude outputs that had to be reversed, redone, or escalated because the agent got them wrong. That keeps the ratio from rewarding volume over quality.
- Baseline output is what the same person, or a comparable person, produced on that work before agents were involved.
An HSER of 1.0 means no gain. An HSER of 4.0 means the squad produces four times the qualified output the human could produce alone.
Worked example
These figures are illustrative.
A customer success lead used to handle about 40 onboarding check-ins per week. She now leads a squad of five agents that handles onboarding outreach, usage monitoring, and early-risk alerts.
| Per week | |
|---|---|
| Total onboarding actions completed by the squad | 260 |
| Actions reversed, redone, or wrongly escalated | 30 |
| Qualified output | 230 |
| Baseline (human alone) | 40 |
HSER = 230 ÷ 40 = 5.75
If the team counted all 260 actions, HSER would read 6.5. The difference shows why quality has to be built into the numerator.
Alternative versions
Teams can adapt the ratio depending on what they track:
| Variant | Calculation | Best for |
|---|---|---|
| Output-based | Qualified squad output ÷ baseline human output | Repeatable work with countable units (cases, campaigns, actions) |
| Outcome-based | Squad outcomes (e.g., retained accounts, activated users) ÷ baseline human outcomes | Work where results matter more than activity |
| Time-based | Hours of equivalent human work completed ÷ human lead hours spent | Mixed work where units aren’t comparable |
How to utilize HSER
Reading the signal
The book’s executive scorecard gives one specific rule: if HSER stalls, redesign the squad. It reads that signal as “the human lead is not gaining enough leverage from the agent mix,” and suggests:
- Retraining the human lead
- Simplifying the agent mix
- Rebalancing responsibilities between agents
- Improving orchestration design, meaning how agents share context and hand off work
Common causes of low or falling HSER
- Too much human time spent on routine approvals that agents could handle within guardrails
- Agents with overlapping mandates that create conflicts the human has to resolve
- Poor data quality causing rework
- Escalation thresholds set too low, sending too many cases to the human
- Too many agents for one person to supervise well
Using HSER with other metrics
| Metric | Question it answers | How it relates to HSER |
|---|---|---|
| Return on Agent (ROA) | Is the squad creating enough economic value to justify its full cost? | HSER is a driver of ROA. High HSER with weak ROA suggests efficient work on the wrong problem. |
| Guardrail metrics | Is the squad safe enough to scale? | High HSER with failing guardrails means the squad is producing faster without enough control. |
| Toil | How much human time still goes to cleanup and routine approvals? | Falling toil usually comes with rising HSER. The book treats toil as an anti-metric to reduce. |
| Escalation quality | Are the right cases reaching the human, with enough context? | Good escalation design is one of the main levers for raising HSER safely. |
Comparison: HSER vs. related measures
| Measure | What it measures | Key difference from HSER |
|---|---|---|
| HSER | Productive leverage a human lead gets from a team of agents | — |
| Labor productivity | Output per hour or per worker | Doesn’t separate human and agent contributions |
| Span of control | Number of direct reports a manager oversees | Counts people (or agents) managed, not the output gained |
| Human-agent ratio | Number of agents per human worker | A staffing ratio. A high ratio doesn’t guarantee high output. |
| Average Handle Time (AHT) | Time spent per customer interaction | A task-level efficiency metric. HSER measures the whole squad. |
| Return on Agent (ROA) | Economic return of agented work against full cost | Measures value. HSER measures leverage. |
Best practices
- Define “qualified output” before measuring. Decide upfront what counts as rework or failure.
- Set a real baseline. Measure the work before agents are added, or use a comparable team without agents.
- Don’t compare HSER across very different work. A squad handling simple routing will naturally score higher than one handling complex negotiations.
- Never use HSER alone to justify scaling. Check ROA and guardrails too.
- Watch the trend more than the number. A flat or falling HSER over two or three review cycles is the useful signal.
- Don’t push HSER up by cutting oversight. Removing human review raises the ratio on paper while increasing risk.
Future trends
- Agent-aware performance reviews. As more marketers manage agents, HR and marketing leaders will need measures like HSER to evaluate people whose output is mostly agent output.
- Ratio benchmarks by function. Expect industry benchmarks for typical agent-per-human ratios and leverage levels in areas such as customer success, content operations, and campaign management.
- Automated measurement. Agent platforms are likely to log qualified output and reversals automatically, making HSER easier to track.
- Workforce planning. HSER-style measures may inform how many people a team needs as agent capability improves.
- Broader “human-agent ratio” thinking. Microsoft’s 2025 Work Trend Index described a future of human-agent teams and “agent bosses,” which points toward more formal ways of measuring how people and agents work together.
FAQs
What does HSER stand for? Hybrid Squad Efficiency Ratio.
Who created HSER? Greg Kihlström introduces it in Marketing Operations 3.0 (De Gruyter Brill) as a driver metric for human-agent squads.
How do you calculate HSER? The book doesn’t prescribe a formula. A practical approach is to divide the squad’s qualified output (work that met quality standards) by what the human lead produced alone before agents were added.
What is a good HSER? There’s no published benchmark. Any HSER meaningfully above 1.0 shows leverage. What matters most is whether it holds steady or improves while guardrails stay healthy.
Is HSER the same as ROA? No. HSER measures how much leverage a human gets from agents. ROA measures whether that work creates enough economic value to justify its full cost. HSER is one of the drivers that helps explain ROA.
Why can a high HSER be misleading? Because a squad can produce a lot of output quickly and still make poor decisions. That’s why the book pairs HSER with ROA and guardrail metrics.
What should you do if HSER stalls? According to the book, redesign the squad: retrain the human lead, simplify the agent mix, rebalance responsibilities, or improve how agents coordinate.
How does HSER relate to the 1-to-5 model? The 1-to-5 model (one human, about five agents) is the squad structure. HSER measures how well that structure is working.
Who uses HSER? Squad leads and Bot Managers use it to tune their teams. In the book’s governance model, the CFO uses it as a key metric for resource allocation.
Related Terms
- Key Performance Indicator (KPI)
- AI Agent
- Human-in-the-Loop (HITL)
- Average Handle Time (AHT)
- Total Cost of Ownership (TCO)
- Employee Lifetime Value (ELV)
- Return on Agent (ROA)
- Human-Agent Squad (1-to-5 Model)
- Bot Manager
- Guardrail Metrics
Listen: related episodes of The Agile Brand
- Omnissa CMO Renu Upadhyay on balancing AI innovation with org chart disruption
- AI and the workforce with Jon Darbyshire, SmartSuite
Read: 34% of companies govern their agents like employees (Martech Futurist)
Sources
- Kihlström, G. Marketing Operations 3.0. De Gruyter Brill. https://www.degruyterbrill.com/document/doi/10.1515/9783112218839/html
- Microsoft. “The 2025 Annual Work Trend Index: The Frontier Firm Is Born.” April 23, 2025. https://blogs.microsoft.com/blog/2025/04/23/the-2025-annual-work-trend-index-the-frontier-firm-is-born/