Every track to professional music performance will include studying music theory, and for good reason. Knowledge of music theory will increase your ability to make critical musical choices that will elevate your playing to the next level. Perhaps the most obvious example of this is improvisation, but music theory knowledge can be applied to all manners of instrumental performance.
Think about how knowledge about a piece of music has enhanced your performance of that work. It's the same for Music Theory - if you know how that piece was constructed on a musical level, you will perform that piece better. Let's say you're playing an orchestra piece. You can listen to the other parts around you, but if you know what role the other parts are playing in the harmony, it allows you to make informed choices about balance, dynamic, and melodic expression. Another example is musical form - if you're preparing a Sonata for performance, being able to study the score and identify the Exposition, Development, and Recapitulation is critical for performing that work at an advanced level.