Everything goes hand in hand. When you have an offense that hasn't scored more than 16 points in four straight games and has shown a tendency to turn the ball over it allows the opposition to play more conservative with their own offense. Especially against the talent Denver has on the defensive side of the ball.
Your opponent doesn't have to be aggressive offensively to try and keep up or catch up. Until the Broncos show the ability to consistently put the ball in the end zone offensively there's really no reason for any opponent to play anything other than close to the vest.
When you have an offense that can consistently put points on the board it also allows your defense to play more aggressively. Those days are gone for right now, unfortunately.