The part preceding the final 「です」 above is not a question even though it contains "elements" of a question -- 「なに」、「いかに」 and 「か」.
「Interrogative word + verb phrase + か」
in this context, as it often does, functions as a noun phrase just as in "I don't know what to eat." in English.
Moving on to my next point..
「A + より（も） + B + です/だ/である」
"B is more important than A.", "B is more desirable than A.", etc.
Notice that there is no word needed in the expression that directly means "important", "desirable", etc.
Thus, the whole sentence means:
If Yamada, who himself is in deep trouble with too much work on hand, said "It is more desirable to think about new (and more efficient) ways to produce than to (just) think about what to produce.", it would not be convincing.