If you read on in your link, you'll see that "[t]he PGY-1 match rate for U.S. seniors was 94.3 percent", while the match rate for non-U.S. medical school graduates is slightly above 50%.

Again from your link:

"This year, 35,969 active applicants vied for 28,849 first-year and 2,908 second-year (including physician (R)) residency positions. U.S. allopathic medical school senior students comprised 18,539 of the active applicants, 352 more than in 2016. "

US medical school graduates have no problems matching, the ~5% who don't usually do so because of their match application strategy, and have the opportunity to scramble at unfilled positions (of which there are ~1300).

There is also a lot of residency spots that go unfilled. I know infectious disease is struggling to get bodies into spaces.