Jay Adams of AtlantaFalcons.com reported that the injury came when Weatherspoon was working with the medical staff:
Head coach Mike Smith said the following, per Adams:
During Sean’s run today with our medical staff, he suffered an injury. We sent Sean to the doctor for some additional testing and evaluation and unfortunately the results showed that he ruptured his Achilles tendon. Sean had been working extremely hard to get back on the field, but regrettably he will miss the entire 2014 season. He will have a procedure done in the near future and we expect him to make a full recovery.
Weatherspoon's absence will have a huge effect on a defense that finished 29th in defensive DVOA (defense-adjusted value over average) last season, according to Football Outsiders. Part of that was down to the 26-year-old missing most of the first half of the season with a foot injury.
Neither Sports Illustrated's Chris Burke nor Rotoworld's Evan Silva were optimistic about Atlanta's chances in the upcoming season:
As Dave Matter of the St. Louis Post-Dispatch pointed out, this is also a cruel blow for Weatherspoon, who's in the final year of his contract. Between his foot injury last year and this most recent Achilles rupture, his value couldn't be much lower:
In each of the last two seasons in which Weatherspoon was healthy—2011 and 2012—he was the Falcons' second-leading tackler. He would've been a major piece of Atlanta's turnaround from last year's disastrous 4-12 finish.
Without him, the Falcons will be deprived of one of their best defensive assets.