The absence of Tyron Smith was costly, but how should the Cowboys address this concern?

In 2015, an injury to Tony Romo derailed the Cowboys season. The coaching staff severely misjudged what they had for backups and the offense went into the toilet as both Brandon Weeden and Matt Cassel offered them nothing. It was a complete mess and resulted in a disappointing year following a good 2014 season where the Cowboys went 12-4. Besides Romo, the team was also without several other players due to injuries and suspensions. Here are the key losses for the Cowboys that season:

This season has a lot of similarities to that disastrous season.