He said he was tested 5 days prior to the test he was caught, was guessing he got lazy thinking he was in the clear and then they sprung another test on him before he could take the masking agent.
There are holes in his story, and a lot of what he said made no sense (he was checking texts, phone calls, had his dogs urine tested (?!))...bottom line is he's just desperate and instead of being a man he's gonna draw this out and play the victim just like Bautista arguing balls and strikes every game.