Playing devil's advocate...the perception may be, inside the Knicks front office, that NY has more talent than Indiana but was just roundly outcoached, from an X's and Os' perspective. Getting beat soundly on transition all series, having inconsistent/failed coverages on pick-and-rolls... are just a couple examples. Meanwhile Carlisle had the Pacers often take Brunson out of the game with blitzing pick and roll coverage (after guarding full court) and leave the Knicks scrambling for offense at the end of the shot clock.
Devil's devil's advocate (angel's advocate?)...while the Knicks probably do have more offensive talent on balance, and compliment that talent with great defenders in Anunoby, Bridges, Robinson, and Hart...it's hard to overcome your 2 best offensive players (Brunson and Towns) being negatives on D. Some of those failed pick and roll coverages could come down to poor execution/choices by Towns, not necessarily bad strategy (hard to know, for sure).
On balance I agree this feels like an overreaction. Thibs did have more success than any Knicks coach this millennium.
Also, the Pacers the last 2 seasons have seemingly taken the mantle of the recent Miami Heat of being the team that way overperforms in the postseason compared to their regular season record.