Antonyms for the phrase "covers bases" would include words such as "negligent," "indifferent," and "careless." Rather than being thorough and exhaustive in their preparations, those who are negligent neglect certain aspects of a task, leaving themselves vulnerable to failure. Those who are indifferent may lack enthusiasm or concern for the task, leading to a lack of attention to detail. And those who are careless may be reckless in their approach, failing to take necessary precautions to ensure the success of their actions. In contrast to covering one's bases, these qualities are antithetical to being meticulous, diligent, and careful in one's planning and execution.