But - I don't know if it's mentioned in this article or not - he only chose to adopt a different identity after the poem was rejected 40 times under his real name. To me that says that his poem was not really good enough to get published on its own. It was rejected 9 times under the new name. I do hate using that as "evidence" because it's not really the best data - you wouldn't send the same poem to the same journal under a second name if it was rejected under the first. At worst you'd be accused of plagiarism. But Alexie did say that the poet's name was one reason he gave it more consideration. So to me, it does seem like it's about the assumed identity at least as much as the poem.
The question is which matters more: the poem or the ecosystem in which the poem exists? In my opinion, there are lots of bad poems that are revered as masterpieces. However, I'm just a guy that doesn't particularly like poetry and my opinion is thoroughly irrelevant. This discussion centers on the fact that some poems are only "the best American poems" if they're considered to be something they're not. It erodes the authority of the art because it reveals that the opinion of the people who should matter may not be relevant, either. in the end, what is "good?"