Look...Elson is a big tall guy that can jump, is fast, has athleticism and is coordinated...he's not a precise executor of defensive schemes, because he didn't have to develop those skills to get to the NBA. His athleticism is enough...
At the age of 30, he is not going to turn into a guy that's always in the right spot, or executes the game plan to precision...and it's foolhardy to expect that of him.
It's like expecting Oberto to turn into a guy that can jump out of the gym...it's just not going to happen...so instead of complaining about what the guy isn't and trying to change it, which is both difficult to do as well as time consuming, not to mention nearly always destined to fail....appreciate what he is and play to that strength.
Elson can play a bad game and still be disruptive, and he can put up big numbers from time to time...that's what he is, that's who he is, might as well accept it and be glad we have a guy with some athelticism to come off the bench.