There's another question here where this is answered, but as usual I can't find it without sifting through a hundred results. (The site search really isn't very useful at all.)
What we found (in the other answer) was that different disciplines have different conventions. In Psychology, for example, the order of authors is that of the amount of contribution, with the last author often being the most eminent scholar who usually has not written or researched anything (for the present study) but provided labs, financing, and thus provided the basis to undertake the study.
In physics or maths on the other hand, and escpecially if the number of contributors is large, authors are conventionally listed in alphabetical order.
There may be other conventions in other academic fields, so you need to specify which field you want to publish in.
In jouralistic writing the order is dictated by the conscience of the author, who might be following what is currently seen as polictically correct (women first) or respectful (older person's first) or, as in your example, whoever the author wants to emphasize.
The APA Manual (2009, p. 19) has the following to say about order of authorship in the field of psychology:
Authors are responsible for determining authorship and for specifying the order in which two or morhe authors' names appear in the byline. The general rule is that the name of the principal contributor should appear first, with subsequent names in order of decreasing contribution, but this convention can vary from field to field. If authors played equal roles in the research and publication of their study, they may wish to note this in the author note ... .
Principal authorship and the order of authorship credit should accurately reflect the relative contributions of the persons invovled (APA Ethics Code Standard 8.12b, Pubication Credit). Relative status (i.e., department chair, junior faculty member, student) should not determine the order of authorship.
What the MLA Handbooks says, I don't know. But Google is your friend.