US escort reclassification brought names into line with fleet roles

Why did the US Navy reclassify Knox, Brooke, Garcia, and Bronstein escorts as frigates?

The change helped harmonize fleet categories with their roles, including the escorts' primary anti-submarine mission.

The change to frigate terminology formed part of an effort to make cruiser, destroyer, and frigate categories more consistent. The ships in the question were chiefly intended for anti-submarine work. Their place in the fleet therefore mattered more to the label than the presence of guided missiles. Reclassification sought to harmonize names with function.