Dreams about sports, such as playing baseball, often symbolize competition, teamwork, and the pursuit of goals. Your feeling of being "very good" at baseball suggests confidence in your abilities and a desire to succeed in your endeavors. The white uniform with dark blue trim may represent purity and professionalism, indicating that you are prepared and serious about your pursuits.

Seeing yourself in the mirror while wearing a soft green turtleneck tucked into your jeans could signify self-reflection and how you perceive yourself. The green color often symbolizes growth, balance, and harmony, which may suggest that you are in a phase of personal development or are seeking a balance in your life.

Overall, this dream could be encouraging you to embrace your skills and talents, while also reflecting on your personal identity and growth. Consider what goals you are currently pursuing and how you can align your actions with your self-perception.