On Sept. 21, Los Angeles Times editor Dean Baquet turned 50 years old. When he stepped out into the newsroom that afternoon, following the daily page-one meeting, he was greeted with a birthday cake and a prolonged, loud ovation. The crowd numbered more than a hundred. Two hundred? It sprawled uncountably out of view, around an angle of the newsroom: columnists and top editors and copy editors all mingling, upbeat and merry. The L.A. Times celebrates birthdays, but not like this; at the edges, it was impossible to hear Mr. Baquet’s remarks, let alone hope for a piece of cake....