No, it is pretty provable.
Data is there. For all the losses we were 3 points of 3rd after the City match - where we lost Romero and Vicario and then our PPG fell off a cliff. Like sheer fall into the abyss. The next game we played was against Fulahm, Forster in goal, Davies and Dragusin at CB - no Solanke even on the bench.... Then Bournmouth and no Dragusin - Davies and Gray at CB and Davies gets injured....
Forster was not a disaster when it came to shot stopping, but in terms of building up play from the back, breaking the press, passing to players in a way that didn't leave them in trouble and with more work to do than was necessary, he is chalk and cheese to even Vicario, let alone the kind of performance Kinsky put in vs Liverpool.
Either way, like I said, the data is there. And more data is there to show how difficult it is for anyone to beat the likes of Fulham, Bournemouth etc.... Not excusing the results just saying they categorically show a huge dip in points collected since the injuries happened.