I can see this being called either way (channeling my inner IAABO).
B *might be* slightly behind with his feet, but I think his torso and arm are ahead and he touches the ball first. And, B is going (more-or-less) parallel to the sideline and is the same distance from it as the ball, while W is moving from inside toward the sideline to get the ball (the ball is between the
VB line and the BK sideline; W is on the
VB line).