Now I'm certain you're just making up reasons to be mad.
Spock is repeatedly depicted as being an established expert across a truly improbable range of topics (including, of all things, brain reattachment surgery). Spock is to basically everything else what Kirk is to "talking computers into killing themselves".
Would the episode have been better if McCoy announced beforehand, "The Mr. Spock! Author of Brain Reattachment Surgery, the standard book for brain surgery! I can't think of anyone I'd rather be dealing with. "
And yes I hold TNG to higher standards than TOS. TOS's contemporary TV writing was Gilligan's Island.
Edit: Also it wasn't Spock doing the surgery. He was only providing feedback to McCoy on the connections. This is the same as how today, brain surgery sometimes needs to be done with the patient conscious so the doctor knows what he's touching and can get immediate feedback from the patient if their speech slurs for example.
No, Spock guided him through the back half of the surgery when the effects of the teacher wore off. He literally told him which instruments to use (oh that tri-laser connector!) and how to proceed. Here's the dialog:
SPOCK: If you will finish reconnecting my speech centre, I might be able to help.
MCCOY: Speech centre.
SPOCK: Yes. That's correct. One thing at a time. Ah, ah, mmm. (normal voice) That's better. Now, Doctor. Try the sonic separator.
MCCOY: Sonic separator.
SPOCK: Yes, I believe I already have some sensation of feeling. Please stimulate the nerve endings and observe the physical reactions, one by one. In each case, I shall tell you when the probe is correct. You will then seal using the tri-laser connector.
MCCOY: Tri-laser connector. Ready?
SPOCK: Ready.
Of course, what the text fails to convey is McCoy's hesitation and confusion, or Spock's confidence as he instructs him on how to complete the surgery.
I... watch far too much TOS...
Edit:
By the way, there is one bit of headcanon, here, that could explain this specific example, so yes, I'm gonna undermine my own point, but hey, what's a pedantic conversation about Trek without circling back and contradicting oneself??
So, the one bit of headcanon is: Spock seems to have had access to the knowledge of the people of Sigma Draconis, given that at the end he starts lecturing the group about the history of those people, with knowledge he presumably acquired by being wired up as the Controller. So maybe he also had full access to the knowledge of the teacher, including the knowledge needed to reattach a brain.
"Yes, I believe I already have some sensation of feeling. Please stimulate the nerve endings and observe the physical reactions, one by one. In each case, I shall tell you when the probe is correct. You will then seal using the tri-laser connector."
That was the extent. He told him what nerve caused which response.
"KIRK: Well?
MCCOY: How do I know? I could have made a thousand mistakes. Sealing nerve endings, joining ganglia. The fluid balance is correct, but I don't know.
(Spock sits up and stretches.)
SPOCK: Congratulations, Doctor. And thank you."
And again, Spock was Vulcan, not himan. Just like Data had broad expertise.
Pulaski was human yet was the Federation's top heart surgeon, top virologist, and cured several blind people who had Geordi's condition. You can be good in many areas. But the best in the Galaxy out of all humans in multiple fields?
But your entire premise that if I don't accept Pulaski then TOS is bad is flawed. As you said Kirk talked computers into burning out with a logic problem. Is there any modern Scifi movie or episode that you think is bad? If so I can say you are wrong because Kirk talked computers into burning themselves up.
If you can accept Kirk, then you can accept Battlefield Earth.