Cause for concern
One of the major flaws of the 2016 Chicago Cubs was leaving runners on base. As a team, they lead all of baseball by leaving 1217 runners on. The MLB batting average for runners in scoring position was .258 in 2016. The Cubs hit .252. Not a huge drop, but below average.
Through six games, the Cubs are 13-53 (.245 avg.) with runners in scoring positions. In other words, that go 2-9 per game. Furthermore, they have left 42 runners on base as a team. The trend of 2016 is continuing. If they want to content for another championship, these stats must improve.
Additionally, the team is not walking as much as before. Sure, the regular players have only four or five at-bats, but for a team that lead the Majors in walks, the lack of taking pitches is concerning. Players tend to be more aggressive in Spring Training as they are getting back into the swing of things. Come time for opening day, things should be back to normal.