At each of the first two playoff events, the cuts for the next round come near the bottom of the field.
Eighty percent of postseason participants made it from The Northern Trust to the Dell Technologies Championship, while 70 percent of players advanced from TPC Boston to this week's BMW Championship at Conway Farms Golf Club. But the next cut will go much deeper, as only 30 of the 70 remaining players will make it to the Tour Championship.
McIlroy lifted two trophies last year at the Tour Championship, but he's an outsider to make a return trip to East Lake. The Ulsterman missed the cut during his title defense at TPC Boston, and now will likely need at least a top-5 finish at Conway Farms to make the season finale as he starts the week in 51st place.
But McIlroy is not the only marquee player starting the week outside the top-30 bubble. Phil Mickelson made the Tour Championship every year from 2007-13, but he currently sits at No. 35 in the points race and is in danger of missing East Lake for the third time in the last four years unless he's able to contend at Conway Farms, where he finished T-33 and T-32 in 2013 and 2015, respectively.
Bill Haas begins the week on the bubble, although he and Gary Woodland are nearly in a dead heat at Nos. 29 and 30. Rookie Mackenzie Hughes is on the outside looking in at No. 31 thanks in part to his win at the RSM Classic, while fellow rookie winners Xander Schauffele (No. 32) and Wesley Bryan (No. 37) are close behind.
While making the Tour Championship grants players a chance to win the season-long title, it also comes with some tantalizing incentives - namely spots at the Masters, U.S. Open, The Open and WGC-Mexico Championship next year.
It's a big cutoff for Charles Howell III, who starts this week at No. 35 and has not played the Masters in his hometown since 2012. Tony Finau didn't get to play Augusta National after his win at last year's Puerto Rico Open, but he will make his Masters debut next spring if he's able to crack the top 30 this week from his current spot at No. 39.
There's also another bubble at the top of the standings, as the top five players heading into the Tour Championship will all win the FedExCup with a win at East Lake, just as McIlroy did a year ago. Jordan Spieth, Justin Thomas and Dustin Johnson appear to be locks to maintain their spots within the top 5, while No. 4 Hideki Matsuyama and No. 5 Jon Rahm will battle for the other two spots against a group of contenders that includes Rickie Fowler, Marc Leishman, Paul Casey and Brooks Koepka.
Making the third leg of the playoffs is the mark of a solid season, but for more than half the field this week outside Chicago, it's where the road stops.