[CarpetBench]

The author expands on what they mean by "strategic" in the following paragraphs.

[dominotw]

I know, but I was wondering if that word is commonly used as a noun in English. I've only seen it used as an adj. Sorry should have been clear.

[elros]

It is still an adjective in this context. English becomes more and more copula-dropping – i.e. leaving out the verb "to be" when it can be implied by context. If you add it back you can see how it's an adjective:

The opposite of (being) unpredictable is (to be) strategic.

[dominotw]

Oh yea makes sense now. Thank you for your comment.

[burkaman]

It is an adjective here. Both "unpredictable" and "strategic" are adjectives.