Curiously enough Pulisić is like the antithesis of Mata as a youngster, or even over the course of his career. Juan has traditionally been a player who was fairly productive because of fine decision-making in the final third, despite having a lot of underwhelming games as regards the general proceedings (especially in terms of technical finesse and playmaking). e.g. he posted 27 Goals + Assists at age 20 for Valencia - which was a highly impressive tally, and was spectacularly productive in his first couple of seasons at Chelsea:
http://www.marca.com/2014/01/26/en/football/international_football/1390757759.html
Goals + Assists shouldn't be the focus for young players since that offers a constrictive prism to judge them. They should ideally be given the freedom to express the full repertoire of their skills with production being a bit of an after-thought. e.g. Ribéry scored 3 goals for Metz at age 21 in his first season in Ligue 1, Ronaldo scored 8 goals and gave 4 assists in 2003/04 (and took 3+ seasons to score his first Champions League proper goal vs. Roma - before emerging as the greatest scorer in the history of the competition with 100+ goals), Sánchez with 5 Goals + Assists combined at Udinese at age 19, etc. Production comes naturally with age for most attackers - as their decision-making improves (this is something Pulisić needs to work on), they have better appreciation for spaces, are able to sniff out chances, become better at sensing final ball opportunities, become a tad bit more selfish, and more prominent in the manager's thoughts and approach, etc.