Earlier quoted context omitted.
I think you’ve got it backwards. MIT used to be brain-draining China, India, Iran, Europe, etc into schools like MIT. The lower numbers mean this is happening less. There are likely multiple factors: becoming less attractive, their domestic options becoming more attractive, more aggressive immigration posture, etc
No. They have it right. Brain drain, by definition, is emigration of educated and skilled labor out of country or region in search of greener pastures. America losing foreigners in education institutions is not 'brain drain' in the classical sense. There is no emigration (the drain) involved. America receiving all those students and skilled labor over the years was brain drain.
It’s brain drain from other countries, especially China. The pipeline was simple: go to a mid tier Chinese university for undergraduate studies, get a masters or PhD from an American university, be advantaged in H1B due to this graduate degree, get a green card and settle permanently. That’s the brain drain. This pipeline has slowed down massively.