You’re right, an evaluation should be judged on how good you met your objectives. But it’s the bits in between that you should also take into consideration to help meet your objectives

Defining a clear strategy and the appropriate tools from your objectives should guarantee the best possible method to meet the objectives - be it to increase sales, change attitudes, gain exposure etc etc.

One thing I’ve learnt all the way through uni is to always plan. In Gregory’s Planning and Managing Public Relations Campaigns she states 10 steps to a PR campaign:

Analysis (of the situation)
Objectives (what you want to achieve)
Publics (who it affects)
Messages (what you want to say)
Strategy (how do you go about meeting your objectives)
Tactics (the tools you’re going to use)
Timescale (how long it will take and when to implement)
Resources (what you’re going to use)
Evaluation (was I successful? what could I do better?)
Review (Basically going round in full circle starting again)

But going back to evaluation. I think PR professionals should use evaluation as a key part of a campaign. Only then will the profession hold the position in management it deserves.