Many teams are playing possession-oriented games now, with goalies that play off the line aggressively and fullbacks which are more into the midfield than during the 4-2-3-1 park the bus era. This often leads to a #6 dropping deep to cover when a fullback bombs forward. The combination of many teams adopting a 3-man backline or having a #6 drop between the centerbacks and having one of them split wider (not to mention how few teams are playing with traditional #9s and 11s in the box) means that crosses from out wide are less effective to create scoring chances. Having the #6 drop further back when a team attacks leads to more room between the backs and the midfield on a counter attack, and having the keepers playing further up the field means that there is less room in the box, more room outside the box, and keepers more susceptible to higher shots from distance.

Just my guess. I would love to see more analysis.