My friend has the XT1053 GSM moto maker using AT&T. He hasn't unlocked or rooted, running stock 4.4.2
Seems when he has wifi on, even though he's not connected to anything, his calls get very garbled, mostly he experiences it when he's driving, as that's when he makes calls on it mostly, and because of that it's difficult for him to check his signal strength in the status bar at that moment. I hadn't heard of wifi simply being enabled causing an issue like that, but seems greatly improved when he has it off. I told him he shouldn't have to toggle off wifi to make a call, maybe he should get it replaced under warranty (or at least call Moto tech support to see if there's some trouble shooting, though I wonder if they'll be of help)
Wondering if anyone has heard of this happening on that model (or any phone, for that matter) I have the XT1058 unlocked, rooted, 4.4.2, Xposed, etc., with no issues. He hasn't tried it with data on, as his data plan is limited, so he just turns on data to check email, then turns it off.