realistically, I don’t think Powell has shut down any more or less than either Bolt or Gay. Bolt has probably shut down more often in the past two seasons than Powell has combined for his career minus preliminary runs.
Powells new found “ineffiecient” start has caused the rest of his race to suffer. He’s almost speed skating in his races, and it’s even visibly apparent that his left leg is failing him when he’s up to speed. Either failing him or he’s compensating for it.