What’s the worst thing to befall a professional athlete? It’s not losing some ‘big game.’ Even worse: It’s falling victim to a curse that can derail an entire career.

The Subway sandwich chain has racked up some remarkable business milestones in the last 20 years.

The Milford, Conn.-based franchise, ,which was a small East Coast operation with only a couple hundred locations in the 1980s, now operates more than 35,000 stores in an even 100 countries, including some 8,000 “non-traditional” stores (kiosks, mobile sites, dual-branded locations, etc.).

The company’s growth has been fueled with some creative advertising, including an ad agency home run when they began featuring a “regular guy,” Jared Fogle, who became the face of the franchise after supposedly losing more than 200 pounds eating nothing but Subway sandwiches.

Subway has also been aggressive about signing up big-name sports stars to endorse its line of subs, soups and . . . uh, that’s about it. Over the last five years, Subway has corralled what are arguably some of the most popular, highest profile athletes in the sporting world.

But there’s is an interesting — and very disturbing — downside: The performers who’ve been signed to Subway deals have experienced a run of bad luck that raises the specter of the dreaded “C-word” that all athletes refuse to discuss, but secretly dread.

Here’s the Subway lineup of endorsers. Consider the evidence and judge for yourself:

  • Michael Phelps. The swimming superstar is the most decorated Olympic athlete of all time, wining a total of 22 medals, including 18 gold medals. He’s set all kinds of world records and won an unprecedented eight gold medals at the 2008 Olympics in Beijing. But his image was been severely tarnished by arrests for DWI in 2004 and a suspension for (allegedly) smoking marijuana in 2008. That latter incident, which was prompted by Internet photos of Phelps toking on a pot pipe, resulted in a loss of an endorsement deal (among others) with Kellogg’s — ironically, along with Frito-Lay, probably a stoner’s favorite brand.
  • Robert Griffin III. The Redskins quarterback had it all going on just three years ago. A former college superstar and Heisman Trophy winner, he came into the NFL as the prototype mobile quarterback destined to re-shape offensive game-planning. But he suffered a serious knee injury, failed to replicate his outstanding rookie year and soon fell out of favor with both teammates and fans, to the point that the Washington Post this week speculated that he will soon be cut from the team.
  • Clayton Kershaw. For the past four years, the Los Angeles Dodgers’ leftie has been arguably the premier pitcher in all of Major League Baseball. He won the National League Cy Young award three of the last four years, led all of baseball in ERA all four years and dominated the regular season like no one else. But when it counts, in the postseason, Kershaw has bombed. In fact, he’s the only pitcher in nearly a century of Dodgers baseball to lose four straight postseason games. As good as Kershaw’s been April through September, he’s totally snake bitten in October.
  • Russell Westbrook. The Oklahoma City basketball star is by consensus the most explosive, most exciting offensive player in the entire NBA. He was touted as the league MVP this season, as he totally carried the undermanned Thunder all by himself — despite a couple stints on injured reserve — and eventually won the NBA scoring title. But his team failed to qualify for the playoffs, his coach Scott Brooks was summarily fired and the future of the franchise is now in doubt.

If this were being decided in court, right about now I’d be resting my case.

But there’s an even more disturbing development that must be mentioned. The current Heisman Trophy winner and potential No. 1 pick in the NFL draft taking place next week, former Oregon quarterback Marcus Mariota, just landed an endorsement deal with Subway.

As a proud Oregon alumnus and Fighting Ducks fan, I have only one world for that: NO-O-O-O!!

Apparently, Mariota is even being honored with a “meat statute” made of Subway ingredients (see photo), which only compounds the anger the Sporting Gods will likely unleash upon his head.

The deal surfaced when ESPN reporter Darren Rovell tweeted out a photo earlier this week of Mariota posing with his edible alter ego. Subway created the bust using materials found in its restaurants, with a jersey made of lettuce, shoulder pads fashioned from bread and a lei made out of cucumbers, bell peppers, mushrooms and other veggies (Mariota is Hawaiian).

Based on what I consider to be evidence beyond a reasonable doubt, Mariota just seriously jeopardized his pro career.

It’s bad enough that his appearance on the cover of Sports Illustrated in January was followed that same week by a full-on thrashing from the Ohio State Buckeyes in the national championship game. Everyone knows an SI cover is the kiss of death.

Now, he’s just piling on the bad karma by hooking up with Subway.

Hope that hefty check and all those free Meatball Marinara (Mariota?) sandwiches are worth it.

Dan Murphy is a food-industry journalist and commentator