The phrase "big time operator" typically refers to someone who is skilled or successful in an impressive way. Antonyms for this phrase might include terms like "incompetent," "unskilled," or "unsuccessful." These terms might be used to describe someone who struggles to make a name for themselves in their industry, or someone who lacks the confidence to succeed in a big way. Other antonyms for "big time operator" might include words like "amateur," "inept," or "novice." Ultimately, the antonyms for this phrase describe individuals who are lacking in some aspect of their skills or abilities, and are unlikely to make a significant impact in their chosen field.