How you feel about the Vikings defense probably depends on which numbers you look at. Has the Vikings’ defense been good this season? Has it been bad? Is it somewhere in the middle? The answer is a bit complicated. There are some numbers that suggest Ed Donatell’s unit is off to a solid start to the year. There are other numbers that indicate the defense has mostly struggled and is an area of concern going forward. It all depends on which statistics you value. Let’s start with the pessimistic view. Using Football Outsiders’ DVOA (an opponent-adjusted efficiency metric), the Vikings’…