New York Knicks
Biggest mistake: Not solidifying the frontcourt
I completely understand the New York Knicks' decision to go all-in for Mikal Bridges. It's hard to blame them for that decision to open the NBA offseason. However, losing Isaiah Hartenstein is going to have a bigger impact on the team than most realize. And because of that loss, I believe the Knicks' biggest mistake this offseason is the fact that they didn't solidify their frontcourt. Think of it this way, the team's backup center at the moment is Jericho Sims. Considering Mitchell Robinson has never been healthy for a complete season, it's not great that New York has little to no depth at the center position.
The same could be said about the power forward position, depending on where they envision OG Anunoby playing. If Julius Randle suffers another injury and misses time, New York becomes that much lesser of a team because of the lack of depth behind him.
The Knicks are extremely talented but because of their lack of depth, they could be one big injury away from falling apart.