You are right. Thanks for your thoughts. I did say "formal writing." By that I mean the thing you send or submit for consideration by others. nowaypablo's essay, for example. Of course writing can be changed and often is, but when you write your letter to the grad admissions department (am_Unition) they are not going to give you a chance to fix it. Your ability to conform to the minutiae of written expression is an elitist way for institutions to decide which sheep-goat combo they want to enlist. I want my students to, at least, be aware of those little things even if they don't subscribe. I'm not even being hypocritical. I prefer to read without being confused or distracted by errors.
So true! There is a time and place to Write Well, Write Correctly. :-) But those situations are becoming more rare. The thinking that "you need to know the rules, and break them with intent and considered purpose." ... like my refusal to put anything inside quotation marks that are not in the original quote. Example: "Yes, I feel similarly" he said. as opposed to "Yes, I feel similarly," he said. I want my students to, at least, be aware of those little things even if they don't subscribe.
Are you 100% sure that the comma after yes was in the original quote? If you are, how do you know that the second comma was not? Of course, do whatever you like. Generally we separate the speaker from the spoken words with a comma. That is why we say, He said, "Yes, I feel similarly." In that case, though, the comma is outside of the quotation marks and, thus, not breaking your self-imposed rule.
So I ain't a writer by any training, but I was under the impression that quotations of the spoken word followed a separate grammar. That grammar is designed to capture details of how the person said something. For example, "Yes, I feel similarly" (and here I follow @goobster's rule) conveys that the speaker said it in a way that separated "Yes" and "I feel similarly". Two ways that could have happened are with a pause or by raising the pitch of "I". Meanwhile "Yes I feel similarly" conveys that speaker spoke in a monotone, or in a breathless rush of words.
I'm working on my first paper! Looking forward to analyzing any differences between my manuscript and the end result that appears in the journal. Look what you've done to me, lil. :D