MEMPHIS, Tenn. — The Grizzlies spent quite a bit of time last season trying to explain the unexplainable: Why were they so good when their best player wasn’t in uniform? Virtually everyone involved, as well as most onlookers, chalked up the Grizzlies’ 20-5 record when Ja Morant didn’t play last season as an anomaly and then as a testament to the organization’s depth and the system coach Taylor Jenkins had put in place. Advertisement The Grizzlies are better with Morant, everyone is certain, because he is so dynamic on offense that he can cover up mistakes. His raw jumping ability…