One doctor described New Orleans Saints receiver Dez Bryant as having "a tough rehabilitation" ahead after he suffered a torn Achilles, ESPN's Adam Schefter reported Sunday.

Bryant and the Saints agreed to a one-year contract Wednesday. On the last play of the team's Friday practice, the three-time Pro Bowler went down and will now miss the rest of the 2018 NFL season.

Schefter cited a study in Foot and Ankle International in which researchers looked at a group of 95 NFL players who had suffered Achilles injuries. For almost 28 percent of those players, the setback was a career-ender.

In recent years, Baltimore Ravens receiver Michael Crabtree and San Francisco 49ers cornerback Richard Sherman returned after major Achilles injuries.

Still, the concern isn't just whether Bryant will play again but also whether he can continue to be a dynamic pass-catcher.

Crabtree averaged 12.9 yards per reception and 57.7 yards per game through his first four seasons before he underwent surgery on his Achilles in May 2013, per Pro Football Reference. Over his next six years, Crabtree averaged 11.1 yards per catch and 52.6 yards per contest.

Sherman, meanwhile, has a 73.2 overall grade on Pro Football Focus, which ranks 24th among qualified cornerbacks, in his first season back from his Achilles rupture.

Sherman is a better comparison for Bryant since the two players are at the same stage of their playing careers. They turned 30 earlier this year, so they were already on the wrong end of the aging curve. Their respective injuries may have accelerated their declines.

Bryant played the 2018 season smartly. He waited until he found a home on a potential Super Bowl contender that has a historically great quarterback (Drew Brees).

He couldn't have predicted a season-ending injury, but his value will take a big hit nonetheless, as teams will be cautious about betting too much on what he can deliver in 2019 and beyond.