Thunder keep their first-round draft pick this year if they finish in bottom 20 of NBA.
They can ensure at least a tie for that spot if they lose out. But if there's a tie, then they have to go through the coin-flip to see if they'll keep the pick.
If they don't keep the pick, it goes to Philly. Philly could have moved up to a loss-column tie with the Thunder today if the Sixers won. But that would have increased the odds of OKC keeping its pick (from 1/2 to 2/3 -- OKC will tie with Jazz for 20th spot if both lose out already; a Philly win would have produced a 3-way tie), and thus decreased the odds of Philly getting that pick.
Apparently Sixers rested key players down the stretch of a winnable game against Raptors today and allowed for a Raptor comeback win. Next-level tanking!