The Liberty’s last tuneup before the season starts later this week isn’t about the final score.  Instead, Sunday’s preseason finale against the Connecticut Sun is a checkpoint for the Liberty. It’s a chance for Chris DeMarco to experiment with lineup combinations and measure how well the team has adopted the basics of the new offensive system. He’ll be looking for chemistry, rhythm and improvements from the team’s first preseason game.  New York’s star-studded roster is good enough to win some games on talent alone. But DeMarco has been adamant since training camp opened two weeks ago that the team can’t skip steps.  The team installing a new offensive flow and tightening its defensive principles should be a slow build, not a sprint.  DeMarco is taking a deliberate and layered approach to introducing new concepts and making changes. He’s prioritizing structure rather than freestyle.…