his technique must have been rubbish. Usain must be packed with high twitch muscles which are what give you explosive power so, especially given his height, he should have been able to absolutely rifle the ball down.
surely a lot of tennis players would make good cricketers. Hard to imagine Federers flawless footwork and hand-eye co-ordination wouldn't have translated to cricket. Nadal not so much as he relies on stamina and power, though deliberately switching hands is very australian and would have made him a very top-handed player which is good for technique. Andy Murray has wonderful hand skills, reactions and innovation on the tennis court so he could have made a great one day player, nurdling cut strokes and reverse sweeps into the gaps. Also, his waiting for the error tactics that so often gets criticised in tennis could have made him one for the long haul, always leaving and looking for only the bad balls. (indeed in a tennis match he actually played a shot that was basically a forward defense to a federer smash, and he won the point)
StinkyBoHoon added 4 Minutes and 13 Seconds later...
Oh, and andy roddick at 6'4 (I think) with his super quick release serve action is surely the best fast bowler america never had.