Does this make grammatical sense?

It makes sense. You could say guiding.

Yes it makes sense to me..I dont think that it is grammatically incorrect.

I think it’s correct. I can’t think of another word to take the place of “in” that doesn’t sound weird.

If you really want to use only a single word, I suppose that “in” is what you want. But I would prefer replacing “in” with “contributing to.” I don’t like the placement of “were,” either. I’d move it to the end. This is just on reading the sentence out of context, however; “were” might be appropriately placed in context.

If I were writing that sentence, I would use “in.”

That’s not the part of it that would raise a question with me, though. Instead I would be puzzled by this: “analyzed what were the most significant factors.”

To me this is ambiguous. It sounds like the significant factors were already identified before being analyzed. This is the same as just saying “analyzed the most significant factors,” so why not omit the unnecessary “what were”?

But in that case, how were they identified? The inclusion of “what were” makes it sound as if ascertaining the “what” were the purpose of the analysis. If identifying them is the result of the analysis, as seems more logical, then I think what you mean to say is “analyzed the factors in Lebron’s decision in order to see which were the most significant” or simply “identified the most significant factors in Lebron’s decision to join Miami.”

Either way, the wording lacks clarity and should be made more precise.

I think you could insert the word “involved” before the word “in”, but I wouldn’t replace it.

Personally, I’d move “were” out of its current position to the end of the clause – it’s not a direct question, so the direct question syntax is inappropriate.

I also like @MrItty‘s suggestion of using “involved” before “in.”

I don’t care for the loose use of “involved.” I would suggest “affecting” over “involved in.”

@Jeruba Hmm… I like “affecting,” too. But my wife, who is an editor, agrees with your earlier suggestion to just drop the words “what were” entirely. She thinks this is the cleanest option. If the words are truly important, she suggests moving the word “were” between “factors” and “in.”

@SavoirFaire, I’m an editor too. I consider the problem here to be one of meaning. First the author must be clear on the thought he is trying to express. Then he can worry about how best to say it. An optimal change here can’t be decreed until we know the author’s intent. As an editor your wife will understand the problem of inferring intent from a poorly, vaguely, or incorrectly worded statement. About half of my editorial marks are queries because I can’t presume to know what the author meant and must settle for pointing out the problem.

I’m betting that the original sentence looked something like:

ESPN analyzed what they thought were the most significant factors in Lebron’s decision to join Miami.

And the script editor thought that it would be clear to the audience that this was just what “ESPN thought”, so only those words were removed. I also agree with @Jeruba otherwise. I think “affecting” or “influencing” instead of “in” would have made more sense, to end up with:

ESPN analyzed the most significant factors affecting Lebron’s decision to join Miami.

@Jeruba Yes, she agrees and likes your suggestions much more than she likes mine!