What's happened to 2017 Wimbledon champion Garbine Muguruza?

It was only two years ago that Garbine Muguruza defeated Venus Williams to win her second career major, at Wimbledon. A year earlier, she won Roland Garros in emphatic fashion, upsetting Serena Williams in the final. No one was expecting Muguruza to become the next Williams after hoisting such historic hardware, but the hard-hitting Spaniard was reasonably expected to be a late-round staple at the Slams.

On Tuesday, when Muguruza lost her first-round match to qualifier Beatriz Haddad Maia, it scarcely warranted mention on the U.S. Wimbledon broadcast. It was merely filler for the time between points of the Roger Federer vs. Lloyd Harris match on Centre Court.

"What's happened to her?" asked John McEnroe on ESPN, after his brother, Patrick, read the 6-4, 6-4 scoreline.

"She's fallen off the map," Patrick replied.

The response was telling in two ways: first, Muguruza's precipitous fall from grace. Seeded 26th, Muguruza was a tournament dark horse for many; instead, she joined Venus and Naomi Osaka as two-time Grand Slam champions to fall in the first round. Muguruza decided not a play a grass-court tune-up tournament, and it showed today: she struck 28 unforced errors and was broken three times by Haddad Maia, who won despite winning just 41 percent of her second serves. Muguruza was given plenty of opportunities to assert her authority, but she failed to even win a set.

But second is the question without a clear answer: Why? Famously erratic, Muguruza is capable of a clunker when her artillery isn't hitting its targets. Last year at the majors, she was pretty consistent—just not in a good way. Muguruza took three second-round losses; her other result was, naturally, a semifinal.

While Muguruza's fourth-round runs at the Australian and French Opens this year were in line with her ranking, an opening-round exit is almost inexcusable considering her success at this event, and her obvious talent. It's the first time Muguruza has lost in the first round of a major since 2014.

At each major, we say there are unseeded players no one wants to face early on, because of their sky-high potential on any given day. Considering what we've seen from Muguruza of late, we should also say the same about seeded players who have the potential to flame out, no matter how bright they've once burned.