In house analytics vs some company who was based out of the UK with guys who never played a down of football are completely different things.
In house analytics have been done for decades. No one who has ever coached a down would be against them because they know the context. Not related to analytics but I remember Ron Jaworski and Steve Young getting ripped at times by coaches and players when they were issuing "grades" or even commentary because they didn't know exactly what a specific progression was.
Yes, and that's why PFF and other "guys that never played a down" do not give grades for "progression reading" though they may try to explain it through the various measurable stats.
How long did the QB have a clean pocket before he threw the ball?
What is his Time to Throw with a clean pocket vs under pressure, completions vs incompletions, play action vs not?
How often does the qb avoid a sack under pressure?
Did the pass hit the dirt 5 yards behind/beyond the receiver?
Did the pass hit the receiver's hands or body?
Does the ball hit a receiver's hands substantially more often when throwing to the left versus right?
How about when throwing 10 yards downfield vs 20 yards down field?
etc.
These are all things that can be quantified by people with little/no football playing experience and none of them require any inside knowledge of assignments to be 90%+ accurate. I'm sure most of the teams that use these services aren't looking at "grades" as much as they are looking at the raw percentages, but to everyone else a grade is a far easier way for them to issue an evaluation.
No one is saying these services are infallible or replace actual film study and no one is saying that there aren't positions that are much harder to quantify, but they are an invaluable tool for virtually every professional program.