Sometimes the grass isn't always greener elsewhere. During the exciting 2018 playoff run for the Celtics, rookie Jayson tatum led Boston an exciting run to the Eastern Conference Finals. Everyone said, "Man imagine if we had Kyrie and Hayward healthy?!" Well Boston did the next year (Hayward wasn't 100% yet, but both former All-Stars were added back into the rotation), and things went south that 2018-19 season.
Then not only did Kyrie leave that offseason of 2019, but so did Al Horford, Terry Rozier, Marcus Morris, and Aron Baynes. In their place Danny Ainge signed a brand new max point guard to lead the team in Kemba Walker.