Brilliant screenwriting. Lonergan waits to deliever the back story right up until seconds before it becomes relevant, leaving you with a holy fuck moment that prefaces an attention demanding 2nd & 3rd act. This story lives in subtext, and is driven by world class performances. The ending, although not what the audience was rooting for, was honest. Lee Chandler doesn't go from A-Z because he fucking can't, that wouldn't be truthful. The character is strong enough that watching him go from A-F is a reward.