I actually got confused between 13/14 and 14/15 (it's very late
), but even if we take 14/15, he was still included for his defensive ability, not his creative ability -- his defensive statistics for that season are again better than Wanyama's, and the gap in dribbles is closed to .1 (from .4) the previous season. Interestingly, there is only one goal between Wanyama and Schneiderlin in terms of end product for that season (4 to 3, both with 1 assist).
Box to box doesn't have to be like Pogba, but box to box does quite literally mean box to box. I.e., you're defensive to offensive -- pop up at both ends consistently.
But if you can see the scope for different interpretations of box to box, why are you against the same logic being applied to DM?
Actually, going from a pure blind statistical viewpoint, you could argue that Wanyama was box to box because of the similarity in terms of stats. We all know that isn't the case, though. So I just can't see any sense in defining Schneiderlin as box to box. He's a ball-winning CM in my eyes. His passing isn't good over long distances, nor great over short distances. Good passing (and variety) is a trait of box to box midfielders. Good ones, at least.