Rule about order in modal + adverb + to be

I am currently reading a book, where I found the following sentences:

The X can be also applied to Y

Later in the book, I find

The X may alternatively be spread over two Y

My question is relative to the different ordering of modal verb + adverb + infinitive, as in "can be also" vs. "may alternatively be", and what is the exact rule.

The most common word order is modal + adverb + verb. The ordering "The X can be also applied to Y" sounds very artificial to me, and I much prefer "The X can also be applied to Y", with the adverb moved to the position immediately following the modal verb.

Google reports a similar result. There are 938,000,000 results for "can also be", but only 14,400,000 results for "can be also". Keeping in mind that the magnitude of results that Google reports for queries like these can be extremely inaccurate, this nonetheless shows that "can also be" is preferred by a ratio of over 10:1.