Thanks for sharing the article. I’ve known the general rule for a long time, but the article cleared up something that had always seemed to contradict the rule:

Only “streets” are subject to the convention. Avenues, roads, drives, and other minor streets do not conform to the alphabetical progression. “Places,” on the other hand, usually appear one block north of the correspondingly lettered street and often share the same first letter.

So now I understand why Quincy Place and Todd Place are in eckington, which is covered by the first alphabet.