phrase request-Talking in completely irrelevant terms to cover up one's lack of knowledge

Solution 1:

I'd say his remarks are obfuscatory; he's engaging in deliberate obfuscation.

Solution 2:

bluffing (or one of its synonyms)

verb
1. try to deceive someone as to one's abilities or intentions. "he's been bluffing all along" synonyms: pretend, sham, fake, feign, put on an act, put it on, lie, hoax, pose, posture, masquerade, dissemble, dissimulate;
Oxford Dictionaries

bullshitting

to ​try to ​persuade someone or make them ​admire you by saying things that are not ​true: You're bullshitting me! Quit bullshitting, will you!
Cambridge Dictionaries Online

As the question specifically mention chess, you may be interested in this publication.

The Bluffer's Guide to Chess: Bluff Your Way in Chess (Bluffer Guides) Paperback – Nov 1993 By Brian Malpass