I disagree. I'm not completely exonerating them of any blame as they have had their own individual poor games and have also made mistakes.
Yet, I find it remarkable (and pretty unlikely) that three proven and competent defenders all suffer a major lull in form at the same time.
I suppose it may just be coincidence, but I'm more inclined to think that there has been a catalyst for their demise: in this instance our approach.
Jagielka is clearly uncomfortable on the ball as Martinez wants him to play, while Stones has been clearly asked to play suicide football at the back.
Baines I'd say is a combination of our defensive setup and its frailties and the fact he's had very little support in front of him this season.
Again they're obviously not without fault, however with a slightly more defensive minded approach that suits their style I think they'd improve.