Arne Engels looks increasingly likely to be heading for the Celtic exit door, but Chris Sutton has warned the Hoops about exactly what they would be losing. That does not mean Celtic will simply accept whatever comes next. That does not mean Celtic should turn down £25 million if West Ham eventually get there. It does mean they need to know exactly how they are replacing him before sanctioning the deal. But Celtic cannot afford to bank the money first and start looking for Engels’ replacement further down the line.