Kyrie Irving is four games into his career as a Celtic. He has underperformed to a degree. Irving's shooting splits (.375/.320/.900) include what would be career-low rates from the field and beyond the arc. That’s quite bad, but the sample size here is small enough to throw them out entirely.
What deserves more observation is Irving's fit within Boston's offense, which is very much a work in progress. The Cavaliers’ relatively stagnant offensive schema instilled a number of habits that don't fit what the Celtics like to run, and Irving is still in the process of shedding them.