This FanGraphs article took a pretty in depth look at the Cards four game sweep of the Cubs... https://blogs.fangraphs.com/the-cardinals-lay-waste-to-the-cubs-2019-season/ Key takeaway... If you think a team dropping more than 50 percentage points in four games calls the playoff odds into question, consider that the Cubs odds of getting swept were 3.4%. The Brewers odds of winning four straight games at the same time was 12.5%. The odds of both happening at the same time are 0.4%, around one in 240. That’s what it took for the Cubs to enter the series with 58% playoff odds and leave it under 3%. Yup - pretty much indicates that percentages are reactive, particularly when you start looking at them in small sample sizes without factoring in how teams are playing at the end of a season. I've thought since early September that the Cubs looked to be on fumes and had a good chance of cratering down the stretch due to key injuries and starting pitching inconsistency aside from the roll Darvish has been on. What it actually took for the Cubs to go from 58% playoff odds to basically doneso in 4 games was them losing 4 winnable games against their main competitor for the division (Cards) while the Brewers beat up on weaker competition and started that stretch only 1 game behind the Cubs in the standings...Cubs were basically losing 3 games in the standings to their postseason competitors with every loss to the Cards coupled with a Brewers win. This swing can happen frequently during the course of a season, but the playoff odds don't swing as wildly when there are still 100, 50, even 25 games left to play in a season. Bottom line - when the math still gives a team a chance and there are head to head opportunities to rapidly climb or plummet the ladder in the standings at the end of the season, throw the playoff odd percentages out the window. For what Fangraphs used for 4 game sweep percentages, I'd argue the Brewers 12.5% odds of winning 4 games during that stretch was far too low based on how they were playing and who they were playing those games against...while the Cubs' odds of losing 4 home games to the Cards at 3.4% was also far too low considering the same things. I'd have put those two outcomes around 20% (Brewers win 4) and 10% (Cubs get swept over 4) - which still makes that outcome very unlikely, but much more possible than 0.4%. This time of year, I like looking at those playoff odd percentages AND the remaining schedule to see just how much control a team has of its own destiny - the Brewers had a very low chance of making even a wildcard berth just a few weeks ago, but their schedule and their competitor's remaining schedules gave them almost full control of its destiny despite a limited number of head to head matchups against teams they were chasing. Because of that, their playoff odds were reactive directly to their performance much more than projective. Cubs had the same situation, just to the opposite effect (almost a lock to done in the blink of a couple weeks).