Fact: A really terrific concept in your query won’t save you if the letter itself is poorly written.
Think of the query letter as a special training ground. A pitch for your novel is really hard to write. Trust me, we agents understand that, which is why most of us aren’t also writers. I’m not crazy enough to subject myself to that torture. LOL.
But you’ve chosen to be a writer so we expect you to perfect every aspect of your craft–and that most certainly includes the pitch in a query letter. It’s your first opportunity to show just how good a writer you are by nailing the pitch.
So if you don’t, agents will simply have the expectation that you are still a beginner and not quite ready for an agent to read your material. Hence, why we pass on 99% of the email query letters sent to us.