Perfect length for a 'Best Picture' Winner
Most of the recent winners have just been barely over 2 Hours
That's why it will edge out "Manchester by the Sea" and "Moonlight"
Manchester by the Sea will need the all-important Best Film Editing nomination to solidify a shot at Best Picture. Only 10 films have won Best Picture without an editing nomination, which covers 82 years of the Academy's 88 year existence. La La Land, Moonlight, and (unseen) Silence look like locks for editing nominations, leaving Manchester competing with Arrival, Fences, Jackie, Lion, Sully etc. for the remaining two editing spots.
Moonlight will also likely check the key indicator categories of acting, directing, and screenplay to stay in the mix, but will need the support of the Academy's technical categories voters likely leaning towards Arrival, Hacksaw Ridge, Jackie, La La Land, Silence, etc. as well as non-Best Picture films like Billy Lynn, Doctor Strange, The Jungle Book, Passengers, etc.
So, the film with the best chance to challenge La La Land for Best Picture (again...with acting, directing, editing, and screenplay nominations, as well as technical category support) appears to be Silence.
Length of film isn't really a measurable precursor statistic. In fact, 55 of the 87 Best Picture winners have clocked in at over 2 hours.
4, 8, 15, 16, 23, 42