We just patched the PTR with a change that loosened the grouping restrictions in Competitive Play for Season 2.

For Master and Grandmaster: You must be within 500 Skill Rating of your groupmates.

For Diamond and below: You must be within 1000 Skill Rating of your groupmates (previously this was 500)

The goal here is to loosen the restrictions somewhat to allow for more grouping while preventing some exploitable behavior and matchmaking issues that are caused by high-skill players who group with lower skill players.

Group restrictions now limit Grand Masters to a skill rating variance of 350 SR.