Normally, I wouldnt talk much about goal difference because I feel that league titles, and relegation is usually decided by winning games. However, I have never known a title race like this, so we cant completely rule out the idea that two or three teams could end up with the same number of points. If we assumed that the season ended today and all of the top four ended with the same points, then Chelsea would finish fourth as a result of having the fourth worst goal difference. However, its worth noting that the numbers between Chelsea, Arsenal and Liverpool are fairly tight. The Blues have +19, Arsenal (+21) and Liverpool (+23), showing that a new striker might allow Chelsea to make up some ground even if they cant match the attacks of Liverpool and Man City. Its just another example of why a new striker could make all the difference at the end of the season, especially with goals scored being taken as a deciding factor after goal difference itself.