Why doesn't our content reliably land anymore?

You say the work is inconsistent, as if consistency were a mood that visits some weeks and not others. It is not. It is a method, or the absence of one. If your team cannot say in one sentence what makes a piece 'on strategy,' you have no standard — only taste, and taste disagrees with itself from one meeting to the next. Notice what you are really asking: why does our content sometimes work and sometimes not? But you already know why. You skip the check against strategy when you are rushed. You guess at what the audience wants instead of asking them. You let a strong personality decide instead of a clear standard. These are choices, made under time pressure, not mysteries. This is harder with others than alone, because now you must agree on a standard before you can even argue about whether a piece meets it. That is not a flaw in the work. That is the work.