CHARLOTTE, N.C. — The PGA Championship for years has been the major that lacked an identity compared with the other three.The Masters is at Augusta National, the only major held at the same course every year. The British Open has links golf. The U.S. Open loves its reputation as the toughest test in golf.And the PGA Championship?“The other one,” Geoff Ogilvy once said in a blend of humor and honesty. Another former U.S. Open champion, Graeme McDowell, was posed the same question years ago and he settled on “the fourth major.”But as the 107th edition of this major starts Thursday at Quail Hollow, boasting 98 of the top 100 players in the world ranking, two-time major champion Jon Rahm raised the idea that the identity of the PGA Championship might be that it has no identity at all.With so much variety — 74 courses since it began at Siwanoy in New York in 1916 — players aren’t always sure what to expect.“When you go to Augusta, you know what you’re getting — same course every year,” Rahm said. “The U.S. Open, nine times out of 10 you know what you’re getting depending on weather. Same thing with The Open, right?“It’s this championship that we change venues and drastically change the way we set it up.”Bethpage Black in 2019 was a beast. A wet week at Valhalla produced the lowest score in PGA Championship history last year. No more than a dozen players finished under par at Southern Hills (2022) and Oak Hill (2023).“You get different things every time you come,” Rahm said. “It’s very difficult to say that two of them are the same.”The U.S. Open goes to Oakmont next month, regarded as a classic course for the second-oldest championship and one of the toughest in America. Justin Thomas, who won the PGA Championship at Quail Hollow in August 2017 and at Southern Hills in May 2022, was asked what he would consider a classic PGA Championship venue.“I don’t think there is,” Thomas said. “And I think that’s what is kind of cool and unique about this event.”Gene Sarazen would have preferred otherwise.Sarazen won his PGAs, when it was match play, at Oakmont (1922), Pelham in New York (1923) and Blue Mound in Wisconsin (1933). And he was concerned that it was getting left behind in terms of prestige.The great “Squire” — the first player to take ownership of the career Grand Slam in 1935 — was at Firestone Country Club in Ohio for the 1966 PGA Championship. It had been played at Laurel …