There's a difference in the timing. Call me silly but I like to think every team begins the year hoping to win. And, because of this, they build their team appropriately. Sometimes they have payroll leftover, sometimes they don't. However, 50 games in, most teams have a real good idea where they'll end up. If you're a contender, you'll likely use that extra payroll to bolster your BL team. If you're not, you'll do something for the future.
Under this plan, you can plan to lose this season, keep a ton of unused payroll, sign your departing FA and essentially start next season with virtually no payroll and a full team. To me, that's a tanker's paradise.