I guess it's a fairly recent thing. Going back a few years I'm sure the Albion only played in their second strip when there was absolutely a clash of colours.
Middlesborough wear red and white. Most of their supporters yesterday were wearing red. Was there a clash between Boro's red and Albion's blue? No. So the Boro' team arrive on the pitch in grey, or was it black .... definitely not red. Why?
OK, so it can only be so that the club can sell more...