The Atlanta Falcons' offensive line struggled in 2014. With four players landing on injured reserve - Joe Hawley, Peter Konz, Sam Baker, and Lamar Holmes - there wasn't a lot of depth. The addition of free agent guard Jon Asamoah and rookie Jake Matthews certainly helped. But an offensive line lacking in continuity will likely have problems.
According to Football Outsiders' offensive line continuity scores, the entire NFL saw a historical drop in "big ugly" health last season. The Falcons had it particularly bad, starting ten different guys over the sixteen game regular season. Their continuity score actually improved from 2013, so they're trending in the right direction!
Offensive line health isn't exactly predictable. Sure, we all saw the Baker injury coming, but these things do happen in the NFL. You can blame it on strength and conditioning all you want. In the end, injuries are inevitable, and all you can really hope for is a little bit of luck. What really matters is quality depth. The Indianapolis Colts had the worst continuity score in the league last year, starting the same number of guys the Falcons did, yet they put a decidedly better product on the field.