After watching his 1500 from last weekend I think it might be a little bit of both mental and physical issues, however I think the mental issues are the same as the past ones.
Physically he looks significantly heavier than he has in the past. There isn't the same "pop" and ease of motion in his stride. Whether or not he's out of shape due to injury/sickness/lack of conditioning etc. I don't know, but he looks like he's running in sand quite frankly. Without knowing the details and history of his training and injuries its really hard to make any accurate conclusion to whats wrong with him.