Part 1: Slower than Nadal in tennis conditions? If you've ever watched Lebron play, you'd know his lateral movement is incredible, he runs straight ahead very fast, and can stop on a dime.
Part 2: I would tend to agree with this, if it hadn't been for Lebron's overall health. He has sprained his left ankle only a few times in his career in the much more bodily demanding sports of basketball.
Part 3: Lower fitness potential? This made me laugh. They run about 3 miles a game- the same as tennis pro's, but are forced to do it in about a third of the time, and get pushed around while doing so.
Part 4: Length and frequency of tennis matches. In tennis there is more just standing around than there is actual play. Matches are also played much less frequently than basketball.
Part 5: Too uncoordinated. Again, you've obviously never watched him play.
And when you're benching 350, and are 6'8", you may never have to even hit a second ball on your serve, ace, ace, ace. Nice try, but before you try to say how bad someone is, you should really watch them play. I never said he would be the greatest player ever in tennis, merely that with his talent and skill assets, it seems he could be dominant, IF he were to play.