Maillage means to mark in squares for a total control or covering. In this context the bigger firms run
( dominate) the market by networking.

idiomatic

To occupy:

To fill up (time or space); To seize possession of and maintain control over by or as if by conquest.

The American Heritage® Dictionary of the English Language


occupy the whole of (WordNet 1.7.1 Copyright © 2001 by Princeton University)

the big firms trump the smaller ones
or
the big firms play their trump card and win over the smaller ones.

The small fish no longer gets through, the big fish blocks the field (with a net).
The small guys no longer get through, the big ones block the field (with a net).

II. V. intr. 1. PÊCHE. En parlant d'un filet. Retenir le poisson. Un filet qui ne maille pas, aux mailles trop petites pour que le poisson s'y engage. Se dit aussi des poissons qui se prennent aux mailles du filet. La sardine ne maille pas quand l'eau est trop claire.

The small fish no longer gets through [because] the big fish catches/holds the terrain/field with a net.

The central idea is that the net retains the fish so that the way to get through is blocked.

I used fish as my first choice as the subject because, in English, we often compare big fish and little fish. "A big fish in a little pond; a little fish in a big pond." But guys also works as a general way to speak of a group.

I just thought this would be a funny, catchy headline. I think a shorter title works better.