i have Three lv 50s. Vanguard scoundrel and a shadow.
But more to the point.... PVP is about CC and mobility commandos are not really lacking in this so know your role, if your not healing keep a distance with push backs and assist with your ability debuffs. and more important use your trooper calldowns like Tenacity, Reactive Shield, Cryo nade and Adrenaline Rush. if your not useing them off every CD then you will just fail.
If your fighting jugs kite them when they pop there defensive CD's use Concussion Charge + cryo nade. and the stockstrike push back to keep as much distance as possible. like i said L2P.