The pattern here is simple: keep talking about the "tightening" race, but always with Clinton the one in the lead. That way, when she wins, the narrative will be, "Trump got close, but he just couldn't close the gap in time."
Truth serum: There was never any doubt that Clinton would beat Trump. This is all Kabuki Theater to grant some appearance of legitimacy to the process. Trump will lose because that's what the press wanted all along. Instead of allowing the GOP to nominate someone with a real chance, they gave Trump all the "free press" he wanted to get him nominated, and are now giggling to themselves over the havoc they have wrought.
Enjoy - Trumpettes. You bought into this charade, hook, line, and sinker.