It absolutely seems like dropping the mic. She's had the job for 4 years and hasn't even approached that level of journalism, criticism or exposure via WaPo outside of Insider. The story was an indictment of the Caps management unlike any other we've seen from her, or any other local journos in years. And it came less than 2 months before she left the job, which in the offseason is nothing. It reeks of someone who's had enough and/or is taking cracks she would never have taken over the previous 4 years, and leaving the position a few pay cycles later strongly suggests a connection.
I am not sure what it reeks of. I do know how these jobs work, though. She does not choose what she writes about or what tact she takes to write it. He editor has that control.
She report to her editor that she is getting information that Oates is OCD about curves of sticks and other things that are driving his players insane and the editor tells her if she can present a story on that. If they approve it, the editor sees the story and changes is how he/she wishes or rejects it if they wish. She does not write what she wants unless she is willing to risk putting in the work and for it to get rejected and filed.
Go back and watch "All the President's men". Woodward and Bernstein had to convince their editors that they were on to something. They were assigned other things and their idea rejected or held for a good while. Each time they found a new thread, their editors had to see the raw data before allowing a write and then had to approve the write before it was published.
So, yes, its possible that she was allowed to write the rip job on Oates because WAPO editors already knew they were moving her. Its more likely that she was getting information that Oates and McPhee were going to get dumped that was being backed up by sources of other writers and they chose to get ahead of that by letter her put together a story using all the junk she had presented during the season.