About that playoff roster, it seems wise to clarify and expand my comments in light of the shorthand Wilner is tweeting (which is not wrong, just has the potential for misunderstanding due to brevity).
The major effect of the Aug. 31 deadline is that it's the last day you can bring a player into the organization and that player be eligible to play in the post-season. There is another intended effect, but that effect has a major loophole. The intended effect is that the pool of players from which you may construct your playoff roster consists of the 25 active players, plus anyone on the DL (either sort) or the bereavement, suspended or military leave list.