Isn't it somewhat the same thing as what you do with numbers? You take past samples and project futures. You look at their past performance and come up with a good, and sound conclusion on what they will do in the future.
Can't the same be done in a less mathematical way with injuries? Take a look at his past injury history, all of the problems he has had and if these problems are becoming or have been chronic or a fluke. Then make a good and sound conclusion about his future health based on this information.
In Johnson' case his injuries are not fluky line drives off the shin (Roy Halladay) or a collision at home plate (Buster Posey). They are chronic arm issues that have plagued him on a consistent basis for many years now. Taking this past information into consideration can we not, even as arm chair gm's, assume a higher risk of the same or similar injury occurring in the future? Thus lowering his value due to massive reliability issues.
When most of these arguments surrounding Johnson were occurring in the off-season, those of us who didn't want him back were assuming it was because the 14M would have gone toward a E.Santana type of signing. Using that thought process can we not argue against offering Johnson a QO or re-signing him at all, thinking there would be no money left for another piece?
I'm happy we didn't sign him, and the result we're seeing now with his injury trouble is the exact reason why. I'm very disappointed the money wasn't spent elsewhere.