Check Game Manual's Economy Sections..There Describe many Factors for Merchandise.
https://www.buzzerbeater.com/community/rules.aspx?nav=Econ...One factor is whether you have a winning team
Other factors include how many domestic players you have on your team, and also how many were drafted by your own team, as fans like supporting local players more than imported talent.
If in a given week your player played in a national team game, fans from around the country will buy their jersey, typically in a quantity proportional to their salary.
If your team has players among the league leaders, you will see a bump in jersey sales from fans of other teams in your league.
and in Relation to that you can also read the Fan Survey:
https://www.buzzerbeater.com/community/rules.aspx?nav=FanS...