I feel Jaylen, Tatum and Hayward are all SFs.
Of the 3, Jaylen is the one best able to play a second position - at SG. I don't know why Jaylen should be the odd one out.
I dont know how you figure that.
Hayward can play SF, can play SG and can even play some stints at the point and small ball PF. He has the playmaking ability and ball handling ability to cover all of those positions.
Tatum can play SF and can play PF pretty much equally as capably, and although we haven't SEEN him do it, I actually think he'd handle the SG spot better then Brown due to the fact that Tatum is just a far better ball handler.
I see Brown as strinctly a SF and I feel putting him at any position other then that is putting him at a disadvantage. As far as pure skill set / talent set, Jaylen Brown in my eyes is basically a smaller Jeff Green, albeit with a significantly better motor.