Well spotted, i just looked on a recent team news article. Think he's been covered by Cyrus Christie who looked a very good player.
Point is, they have cover that seems as strong. We had cover for Bong, then lost him (Rosenior), likewise with Lua Lua (losing March) etc.
If we lose...
Derby have lost Will Hughes and Craig Bryson - the only notables i think. Both are central midfielders, and with Johnson, Butterfield, Thorne, and Jeff Hendrick they have more than enough depth to cover.
Middlesbrough have only really lost Alex Baptiste, who isnt that good anyway.
So no, is...