De Boer was at Inter for like three months anyways. Gabigol hardly impressed their other managers either. He simply wasn't good enough and that has nothing to do with De Boer.
I'm not sure if you've missed the past few years, but Milan hasn't been in the CL for five years now. This is their normal level and they've been irrelevant for years already.
They've done great job at getting worse during the last few years.
Szczesny and Allison ---> Olsen and Mirante
Pjanic, Radja, Strootman ---> NZonzi, Cristante, Pellegrini
Salah ---> Ünder
So it seems Bakayoko won't become
You simply don't touch the ref, especially not in that manner. Everyone who plays football should know that. Clear red.