I don't understand... do you find the lens sharp enough (yourself?), or do you suspect that the lens is faulty because it was not performing to your expectation?
As to the lens tends to be out of focus sometime might be because of your own technique and not the lens' problem. If you are shooting at moving subject at a shallow DOF, when that subject was out of the plane, of course you get out of focus shot.
As Rhino pointed out, Sharpness is decided by the user him/herself. Each person's acceptable sharpness differs. The OOF may also be user technique problem. If it's the user technique problem, even with the 'original' 70-200 f2.8 also will get oof.
What I do is, get the WB of the stage before any of those coloured lights are on, use this shot as the base for your "true" white. Then set the custom WB based on this shot. After the CWB, just continue to shoot as per normal..
And shoot in raw, and should there be any changes to the WB, just adjust the first one, then mass apply to the rest (can be done pretty quickly in LR, Sync all). This should get you closer to what you see....
Again... nobody know for sure... bcos nobody know what setting you are using, what is the environment those shots are taken in, what is the condition, etc... so nobody know if that lens is sharp enough, even if he/she had another copy of the lens. The only way to test is to mount the same camera on a sturdy tripod, then take two different copies of the same lens, mount them one by one to the test camera, took a couple of shots at the same target at a controlled environment, then you can tell if the lens you got is sharp enough... even then it is not really representative.
Dear TS, in your quest to determine the sharpness of your purchase you have chosen a set of challenging conditions to test it. Try again in better light and use a tripod in order to eliminate the other main cause of blur images i.e. shaky hands. Good luck.
are there easier ways to obtained 100% cropped photos from lightroom4, than just crop using the boxes icon on the develop section, by guessing the 1:1 crop and then slowly adjust my cropping up to 1:1?