In addition to lingering pains and psychological uncertainty about the knee providing distraction, there also remains the likelihood that Welker is still being bothered by what's usually the primary obstacle in recovery from this type of issue, that of the slow restoration of proprioception to the joint. Proprioception is a function of the nervous system that tells the brain information about the body's muscular and skeletal systems positioning relative to itself. Its the reason why you can touch your nose with your eyes closed as easy as if it were open, and why you don't need to consciously think about how to best stabilize your knee when you're running, you just know.
The ACL is full of small proprioceptive nerve endings that send signals back to the lower brain about its mechanical status. When the ACL tears, these nerves are torn, and the brain no longer gets the signals it relies on to autonomically keep the knee stabilized while running and cutting. Fortunately, our brains are able to adapt to the incomplete information its getting from the knee and learn to use the proprioceptive nerves from other parts of the knee -- the meniscus, patellar tendon, undamaged ligaments -- to perform its regular motor functions.
This takes requires both time and specialized training, however, and is why athletes are usually still in the process of recovery over a year after the initial tear. While playing with incomplete proprioception in his knee, Welker has had to get used to constantly devoting some of his more active, conscious attention to what's going on with his knee. Nothing he does with his knee is as quite as instinctive as it was, and this throws off the rest of his playing mechanics that used to come so automatically.
The fact that he's played through this as well as he has over the course of the season is the anomaly, not the fact that he's still not 100%.
