Unmasked: The Scrabble Elf of Somerville

David reveals his true identity: Yes, he's the guy who replaced all the missing letters in the Diesel Cafe's Scrabble set. And:

Across the 'ville at Bloc 11, I found an even more perplexing situation, a set with 133 tiles, 33 more than regulation. But it wasn't pure surplus, there were still tiles missing, such as both of the Bs normally in the set. So I contributed the missing tiles and set the excess aside, returning another scrabble set to 100-tile perfection, at least for now.