There are different shards in the Blitz, the Beginner and Veteran Shards which is based on Commander Level. We separate new players who are below level 60 on a Beginner Blitz since they do not have an option to use the Blitz Sim yet.

When a player in the Beginner Blitz reached Level 60, they will be moved to a Veteran shard by their next Blitz and unlock the Blitz Sim feature. Players will also see some changes with the rewards and some differences with your rank as there are more competitive players in the Veteran bracket.