When Josh Hart is on the floor for the New York Knicks, it completely ruins their offensive spacing, and the Boston Celtics are built perfectly to take advantage of it. Boston's lineup is full of incredible defenders, all of whom are capable of making New York pay for having Hart on the floor.
Hart has never been a great three-point shooter. This regular season, Hart shot 33.3% from the field on 3.3 three-point attempts per game. In the first round against the Detroit Pistons, however, he did shoot 50.% from deep. But he only took 2.3 per game, which is very low volume.
Boston is more than comfortable sagging off of him if necessary, which opens up a ton of options for them on the defensive end.
The Celtics' plan to guard Josh Hart suffocates the Knicks' offense
Rather than guarding Hart with Jayson Tatum, Jaylen Brown, or one of their guards, the Celtics almost always stick their center on him. When the starters are in, that's Kristaps Porzingis. When the bench is in, that's either Al Horford or Luke Kornet.
This allows Porzingis (or whoever is guarding Hart) to play a free safety role, roaming over into the paint to stifle drives from Jalen Brunson and the rest of the Knicks' lineup.
Hart has room to shoot open threes, but more often than not, he simply cuts into the paint, further destroying New York's offensive spacing. Porzingis and Kornet, in particular, have been incredible rim protectors this year, so having them guard a guy who isn't a real three-point threat basically gives the Celtics a 4-on-5 situation on defense.
There's always a chance that Hart has an incredible three-point shooting, similar to what he did against the Philadelphia 76ers last year, but at that point, Boston would simply adjust their coverage.
Josh Hart's spacing also hurts Jalen Brunson
To make matters worse for New York, the fact that the Celtics are comfortable guarding Hart with their big man means that Tatum ends up matching up with Karl-Anthony Towns.
And since the Celtics would be more than comfortable switching Tatum onto Brunson should the Knicks run a Brunson-Towns pick-and-roll, New York ends up running more actions with Hart as the screener.
But at that point, the Knicks are left running an offense that completely ignores Towns, Mikal Bridges, and OG Anunoby.
Hart's mere presence on the floor absolutely destroys the Knicks' offense against this Celtics lineup.