I don't think changing a players number has any correlation to merchandising. That's just a little bonus for supporter and as the BB GMs have often stated, there is no training, or monetary advantage to having supporter. It just provides little quirks that are fun to have and make certain things easier.
I personally think the PR manager makes a big difference in merchandise as mine last year was about 20K MAX but its at like 34K this season, now that may be because i have last years draftee still and i won the season and i still have this season's draftee but i'd like to think that he makes a big enough difference to be worth the extra couple grand.