It's that and the fact that most teams have made the conscious decision to sit their starters out of preseason games. It appears they prefer to use the first 3-4 weeks of the regular season as preseason now.I see a lot of poor executions by offenses all over the league. There are some standouts like KC and MIA, but overall the execution is poor. Whether that's because of QB, OL, QB/receivers chemistry, etc.
The new CBA that limits padded practices really is the reason why these offenses look out of sync early in the season. They don't have enough reps. We should see offenses improve as the year goes on unless the QBs are horrible.