I wish I had seen this thread before yesterday because then I would have given my opinion without looking like a Monday morning quarterback... so if I had to answer this question without yesterday's announcement, I would have said he was juicing. The reason why I believed he was juicing has nothing to do with stats or how he went from average player to all-world player back to average... it has to do with something he once said...
Ortiz was once asked about if he had ever taken steroids. He said something like (paraphrasing) "well, when you train in the Dominican Republic, you take all sorts of stuff and sometimes you don't really know what it is you are taking so you don't know how you will test..."
As soon as I heard that interview, it made me believe he was juicing. Obviously, yesterday's events only confirmed that.