The Apertura 2015 saw Sosa become the star man for Pumas and became only the 5th pumas player to score 10 or more goals in the short tournament format, scoring 10 goals. He also added 7 assists during the regular season. On December 9, 2015 Club Universidad Nacional tied Sosa down for another three years to the club.
The Apertura 2015 marked Sosa's rise as Pumas' main player, achieving a milestone by becoming only the fifth Pumas player to score 10 or more goals in the brief tournament format. He also provided 7 assists during the regular season. Subsequently, Club Universidad Nacional decided to retain Sosa for another three years.