Sky Sports pundit Paul Merson has sent a warning to Chelsea ahead of this summer’s transfer window. Chelsea find themselves in a position where they may have to sell players at the end of the season because of profit and sustainability rules. In terms of potential departures, then, the likes of Raheem Sterling and Conor Gallagher have both been linked with exits. The former is reportedly attracting interest from MLS, while it has been claimed that the latter was recently scouted by Newcastle United. Sterling and Gallagher have both been key players for Mauricio Pochettino this season, making 4…