Hi Lee,
As of now it seems to be a personal conscience decision.
Most NFL, NBA, soccer jerseys for any team have a player's name on the back.
So some brothers/sisters may buy a jersey just showing support of their favorite team and the jersey may have a player's name on the back.
Now if a brother/sister feels uncomfortable having a player's name on the back, they can order a jersey with no name or have their own name put on the back.
But if a brother/sister has a jersey, it does not automatically mean that they worship or idolize the team.
And if a brother/sister has a jersey with a player's name on the back, it does not automatically mean that they worship or idolize this player.
Now if a brother/sister has MANY types of pictures, posters, jerseys, etc, of 1 specific player, they may need to meditate on this and consider if they are "idolizing" that player?
However, we can all be a little excessive about things.
So even if a brother/sister has many "fan" items of a specific player, while they need to be cautious, this still does not mean they "idolize" the player and are guilty of a serious sin.
Remember the famous tennis player Boris Becker ?
For some Witnesses who enjoyed tennis in past decades when Becker was playing, he may have been their favorite player. Maybe some brothers/sisters even had some "fan" items of Becker, like a shirt, a racket, etc, with Becker's name on it. But was that a form of "idolizing" a player"?
Here is more of what "idolizing" a player may look like.