The phrase "are the back of" implies a sense of support or physical location. Antonyms to this phrase could include "in front of," which suggests an opposing direction or position. Other antonyms may include "not supportive," "detrimental," or "hindering." These words convey a negative connotation in contrast to the positivity associated with the phrase "are the back of." Using proper antonyms in writing helps to create a more varied and nuanced vocabulary that can convey different emotions and tones.