#1 His overall dominance

Across Europe's top five leagues this season, no player comes near Messi. His eternal rival, Cristiano Ronaldo is performing below his standards after moving to Juventus with 26 goals in all competitions. Reigning Ballon d'Or winner Luka Modric also looks a shadow of himself in a mediocre season with Real Madrid.
So, Leo clearly belongs in a league of his own at the moment. His effectiveness in the team across every competition this season has been tremendous and most times, Barca look ordinary whenever he is not on the field.
Being the talismanic figure of the team in terms of creativity and goals, Leo has proven beyond every doubt, his importance to the Catalan giants. Despite the plethora of midfield talents and strikers in Europe, Messi has outperformed all of them in terms of creativity and goals this season. He has mastered the very best way of playing football as highlighted by his performance and statistics.
The attacker has recorded 46 goals and 23 assists to his name across all competitions so far. He is the leading scorer and provider in both Spain and Europe this season as well as the leading goalscorer in the Champions League. With Barcelona in the semifinals of the UCL as well as a few games left in both the La Liga and the Copa Del Rey, he will surely increase his numbers before the end of the season.