In a recent study from Germany, electrical activity of the erector spinae muscle alongside the spine was tested in amateur tennis athletes. Some of the athletes had LBP. Others did not. The researchers did not find a correlation between spinal mobility and muscular flexibility with LBP.
When analyzing the data individually (instead of together), erector spinae flexibility had a significant relationship to LBP. When combined with spinal mobility, this effect was not significant.
It's likely that a neuromuscular imbalance is the real problem. When the muscles don't contract at the right time (too soon, too late) or they are activated with too little power, an imbalance occurs. This imbalance is the subject of many new studies as scientists continue trying to find the cause of LBP.
Until we know more, a general program of conditioning, strengthening, and stretching is advised for overall fitness and prevention of back pain.