"Be par with" is an idiomatic expression that means to be equal or similar in status, level, or quality. The antonyms for this phrase could be "fall behind," "lag behind," "trail behind," "be inferior," or "be subordinate." These words imply that someone or something is not able to keep up with others or is at a disadvantage compared to others. In a competitive environment, falling behind can mean losing out on opportunities or failing to achieve a goal. Thus, it is important to stay ahead and strive for excellence to maintain one's standing among others.