Media agency reviews in 2027: what's changed and what never will

Agencies became sellers, fees moved off hours and search split in two. What still decides a good agency relationship, and how to review it.

We've sat on both sides of the table in media agency reviews. From one side, you watch a few weeks of meetings decide where a very large budget goes for years. From the other, you see how much of that decision was settled before the first agency walked in. Both teach the same lesson: the pitch is the smallest part of the job.

A lot of brands are about to relearn that. 2027 is shaping up as a heavy review year, and the reasons are different this time.

Why 2027 is a review year

By July, COMvergence figures cited by Digiday showed about $13 billion in media spend had already moved in 2026, with another $11 billion under review. At least 27 of the world's 100 biggest advertisers hadn't reviewed their media in more than seven years. Forrester predicted that 85% of US consumer marketers would review their media agencies this year.

Contract timing explains some of it. Most of it is that the agency market has been rebuilt underneath clients. Omnicom closed its acquisition of IPG in late 2025, cut thousands of roles and retired three creative network brands. Omnicom Media now runs six media agencies under one roof. If your agency's parent changed hands, the people on your business probably changed too, whether or not anyone told you.

What has changed

Your agency is also a seller. Principal media, where the agency buys inventory and resells it to you, is now mainstream. In the ANA's March 2026 report, 58% of advertisers had used it in the past year, up from 47%. Ninety percent weren't sure the agency's recommendations served their interest, and almost a quarter didn't know whether their contract covered it. Principal media isn't the problem. Undisclosed principal media is, and a review is when you have the most room to set the rules.

How agencies get paid. A WFA study published in October found paying for hours is now the main model for only 19% of global brands. Fixed-fee and output models have grown to a third. Twenty percent of brands have already changed their terms because of AI, and 61% plan to. When automation takes hours out of planning, buying and reporting, somebody keeps the savings. Your RFP should decide who.

Search has split in two. People now ask AI assistants what they used to type into Google. Omnicom's own research put generative AI at nearly a quarter of searches last year, and more of those answers end without a click. Being the brand an AI recommends (answer engine optimization, or AEO) depends on paid search, content, PR, product data and site structure together. In most companies nobody owns it yet. Put it in the review scope, or it will fall between your agency, your SEO partner and your web team.

Creative and media are converging. AI can produce hundreds of versions of an ad, and the platform decides which one runs. The handoff between creative and media agencies is now a performance issue, not a process one. Ask every candidate how they'd work with your creative partner, and test the answer.

Measurement sits inside the decision. In an Ebiquity and WFA survey, only 15% of marketers said effectiveness results drive budget decisions, and just 14% said marketing and finance fully agree on what effectiveness means. An agency that can't connect spend to results on a timeline your CFO accepts is a buying service, and should be priced like one.

The roster has more moving parts. Retail and commerce media, connected TV, creators, in-house teams, and platforms happy to run your campaigns with their own AI. The agency's job is less about owning every dollar and more about running a mix it doesn't fully control.

What hasn't changed

The things that decide whether an agency relationship works are the same ones that decided it fifteen years ago.

Who shows up. Senior people at the pitch, junior people on the account. It's the oldest complaint in the business because it's still true. Name the team in the contract and give yourself approval over changes.

Trust. Will they tell you something you don't want to hear? In our experience, the agency that lasts is usually the one that pushed back during the process, not the one that agreed with everything.

Chemistry, with guardrails. Forrester's "Ditch the Pitch" report urged marketers to weigh chemistry more heavily. It matters. Score it next to commercial terms, not instead of them.

Switching is expensive. Forrester estimated US agencies spend about $12.5 billion a year on pitches, and clients lose months to onboarding. A review run only to squeeze a better rate rarely pays for itself.

Review as maintenance, not overhaul

Media relationships are already the shortest in marketing. ANA and 4A's research puts average tenure for media-only agencies at 3.7 years, against roughly seven across all agency types. Most of those relationships don't fail suddenly. They drift.

The answer is regular maintenance, and the reason isn't only cost. Your business changes, the technology changes, and the team you hired three years ago was built for a different job. You may need more senior strategy and less execution, or the reverse. You may need roles that barely existed the last time you went to market: a commerce media lead, an AEO specialist, someone who can run AI workflows.

The other half is whether the agency is keeping up. New platforms and tools arrive every quarter, from retail media networks to AI planning and answer engine tools. Good partners train their people on them before clients ask. Ask who on your team is certified on the platforms you use, what they've learned in the last year, and what the agency changed because of it. If the answers are vague, the team is coasting on what it knew when it won the business.

A sensible rhythm:

• Every year: a health check on results against agreed measures, team stability and seniority, skills against the platforms you now use, and fees against scope.
• Every year or two: a contract and principal media audit, plus a market check on fees and terms.
• Only when needed: a full review, because the health check says the relationship can't be fixed or the business has changed shape.

Done this way, a review stops being a once-in-five-years event that freezes the marketing team for half a year. It becomes ordinary management. And when you do go to market, you know exactly why.

What a good partner looks like

No single type of agency wins. Holding companies bring buying scale and data. Independents bring senior attention and fewer conflicts. The ones worth hiring tend to share these traits:

• Transparent: principal media disclosed, opt-in and reported line by line.
• Priced on value: fees tied to outputs or results, not just hours.
• Senior and stable: a named team that stays.
• Always learning: people trained on new platforms before you have to ask.
• Fair on exit: your data, accounts and platform seats stay yours.
• Accountable: a measurement approach your finance team will sign off on.
• Proven to change: they can show what they changed in the last two years.

Before you start a 2027 review

What we'd do before any agency hears about it:

• Decide the operating model first. What stays in-house, what goes to an agency, and what you buy directly from platforms. Otherwise agencies will design your organization around themselves.
• Write the internal brief. Why you're reviewing, scope with spend attached, the fee model, the contract terms you won't trade, and scoring weights agreed upfront. Here's what that brief should cover.
• Get the final decision-maker's objectives on paper early. The person who signs is often in a different office from the team running the process. If their priorities only surface at the final presentation, the process restarts.
• Bring finance in from day one. If marketing and finance disagree on how success is measured, no agency can fix it.
• Give the incumbent a fair shot. Sometimes a review resets a relationship rather than replacing it, and that can be the best outcome.
• Plan the transition as carefully as the pitch. Data, accounts, platform seats and a 90-day handover, written into the contract before you need them.

For the two contract terms that will matter most next year, see our notes on the principal media clause and AI and agency fees.

We've run these reviews from the client's side for consumer, restaurant and automotive brands, and we're paid only by the client, never by an agency or a media owner. If you're planning a 2027 review and want an independent read on the brief before it goes out, that's a short piece of work.

Sources: Digiday, How Mediasense and other consultancies are girding for a busy second half, Digiday, AI's impact on search forces agencies to rewrite the marketing script, eMarketer, FAQ on ad agencies: consolidation, AI disruption and what's changing in 2026, Digiday, Omnicom Media's Adamski on principal media, ANA, 2026 Principal Media Report, VideoWeek, Global brands are ditching labour-based agency fees, finds WFA, Digiday, Forrester offers solutions to a very flawed pitch process, ANA, Client-agency relationship tenure has doubled since 2016