What's the deal with David Ortiz..?

He tore his meniscus in his right knee which is his power leg for when he hits. His numbers have gone down especially power numbers but he's been playing on since last year. He says he has good days and bad days. My opinion is that he won't get the surgery until after the season because he is only a DH and he has said he doesn't want to until the season is over. I think we should trust the guy since it is his knee and he has been playing on a bad knee for more than a year now.