Josh Koscheck retired on Thursday, perhaps completing the domino chain of aughts era fighters who have decided they are done slinging leather in a cage for money. His announcement, made on Thursday’s edition of The Luke Thomas Show, follows those made by Johny Hendricks, Rashad Evans, and Michael Bisping, making it three ex-UFC champions and a perennial contender that have called it quits in a one-month span. Quite a four-piece combo. While fighters come and go, it’s rare to suffer such a major drainage of talent in one short burst.

This is no small loss; even in a sport with many distinct characters, the members of this quartet were both easily identifiable and worth your emotional and financial investment.

Bisping was perhaps the most colorful, a brash Brit who shot from the lip, unafraid of incensing an opponent or even a nation. A foundation for European expansion, he ran the risk of being forever underrated in importance until his late-career surge capped in a stunning UFC middleweight championship win. This was a guy who always created a show, raised the stakes, and gave of himself to the point that fears for his long-term vision finally convinced him to walk away.

Evans was a criminally under-appreciated fighter from the get-go, an afterthought in The Ultimate Fighter season two as a blown-up heavyweight, who somehow managed to navigate his way through to win the tournament. With wins over Bisping, Chuck Liddell, Forrest Griffin, Tito Ortiz,Quinton Jackson and Dan Henderson, Evans boasts a Hall of Fame-resume to go along with his thoughtful and loquacious personality.

Hendricks, for a time, had dynamite in his left hand, using it to climb to the top of the welterweight division until the scale became his undoing. Remember when he skidded Martin Kampmannacross the canvas? Remember his war with Georges St-Pierre?

And Koscheck? He was the dude you loved to hate, the one who understood the role he was playing and its value to building an event. There wasn’t a fan (or opponent) he couldn’t get to boo him.

When a superstar like Ronda Rousey or Liddell retires, there is usually an outpouring of concern about who might replace them. This is a star-driven business, after all, so it is a fair question. But rarely does the same fear arise when names just a rung below call it quits. While none of those names ever reached the bona fide, grade-A, top-draw status of the Rouseys and Conor McGregors of the fight world, most were, at their best, capable of holding up the whole tent.

From 2008 to 2012, Evans had a stretch where he helped build two pay-per-views that sold 1 million units apiece (against Griffin and “Rampage”, respectively), and a third that sold 700,000 (against Jon Jones).

That was as good as it got for any of them. But still, they served the same roles as best supporting actors in the Academy Award race. These were reliable pros who were more than capable of stealing the show if the star failed to bring his or her best self under the bright lights. Koscheck once melted Yoshiyuki Yoshida with a vaporizer right hand. He once won a round from St-Pierre, a rare feat for any “GSP” adversary. Hendricks once stopped Jon Fitch so quickly it looked like an optical illusion. Bisping’s left-hook KO of Luke Rockhold was straight out of a fairytale.

There were so many wins, so many moments, yet poof, they’re gone, off to the history books.

And we’re left to wonder, who will replace them? Someone will, sometime, even if it’s a slow build for the kids on the way up. There are more fights, more fighters, and more events to wade through, making it difficult for singular talents to make their way through the noise. But gravitas takes time. Seniority takes time.

Maybe kids like Brian Ortega, Cody Garbrandt and Francis Ngannou will one day reach those heights. Maybe veterans like Chris Weidman, Joanna Jedrzejczyk and Stipe Miocic are stepping into their shoes. Maybe legends like Donald Cerrone, Frankie Edgar and Robbie Lawler — already there — are the next senior wave that will crash to shore, the ones that we should be appreciating before they too say good-bye.

These are all names that matter, benchmarks used to measure time and money and success. As fans and viewers, we watch them with awe and revel in their achievements, often forgetting that it is all very temporary, that they are passing through, individual pages in history.

Koscheck, Hendricks, Bisping, and Evans, a four-pack of building blocks with a laundry list of accomplishments and the personalities to matter. Damn, that was a fun time, wasn’t it? They’re barely gone yet missed already.