Just speculating, but maybe the Cubs have been playing Heyward to possibly create an iota of trade value prior to the deadline. If Heyward got hot over a 2-3 week span, some playoff team might be willing to give the Cubs an iffy prospect. Getting something is better than nothing.
But I would agree. If Heyward doesn't start hitting, they should let him go after the break. Doesn't matter how good of a clubhouse guy he is. The reality, if the Cubs waive him, some playoff team will pick him up on the cheap. He a good clubhouse guy and defender. They can hope he finds his bat in September. If not, he gets left off their playoff roster.