Opening up your trunk and mid section can have some seriously positive effects. Your lats tie into so much from your upper back and neck all the way to your lower back. Loosening up this area will help everything from your front rack position to your position in lock out and even your air squat will improve through being able to keep your chest more upright. Underneath those are your obliques. These can also be a huge cause for concern. If they are not strong or active you will not be able to stabilize at all during any type of over head or heavy loaded squat. Work you mobility through band distraction and finding your corners as well as oblique strengthening and soft tissue work and see if a variety of movements improve.
30 Clean and Jerks 165/115