In the following sentence, why does "неизбежным следствием" appear in the instrumental case.

На фоне сегодняшних зарплат они выглядят копейками: неизбежным следствием симбиоза футбола и большого бизнеса явилось то, что контракты растут в геометрической прогрессии, обновляя рекорды едва ли не каждый сезон.

I searched through my Russian grammar book and couldn't find the answer. It lists the following as uses of the instrumental case:

1. To express the instrument or means by which an action is performed
2. To denote the agent of action in a passive sentence
3. To denote the force responsible for an action in impersonal sentences
4. To express the manner or way an action is performed
5. To denote similarity
6. To express means of travel
7. To denote a route taken
8. To denote the time when something occurs

Appreciate the help, thank you!