虫食い状態 is a Japanese way of expressing data fragmentation. The reference link explains as follows:

たとえば、ソフトのインストールとアンインストール、データの保存と削除を頻繁に繰り返していると、ハードディスクの中でデータが記録されている部分と記録されていない部分が混ざって、いわば虫食い状態のようになる。

In the sentence quoted (a repeated downloads context), one has to take into account the reason why 虫食い状態　(a colloquial but visually expressive term with somewhat undesirable connotations) is used instead of the neutral, analytic, conceptual technical term 断片化.
'Fragmentation' is an unavoidable and accepted constraint of the memory allocation systems devised so far for immediate, provisional static binary data storage.
The point that the sentence quoted seems to make is that, when it becomes excessive, that memory fragmentation becomes undesirable, (since its slows down data retrieval and computer processing and as part of routine good maintenance practices, always has to be reversed through mem block allocation reshuffling to consolidate the data that belong together.)
Thus, 'overfragmented' would be my choice, as I see it. Not yours, dear colleagues?