The first of those is subjective but the second one is not, and FanGraphs' Bill Petti did some work. Cutting to the chase:
Bottom line, this initial look does not suggest that extreme ground ball pitchers are more prone to catastrophic arm injuries compared to their counterparts.
Now, this wasn’t a comprehensive study–it was a quick look at the data on a Saturday afternoon. Others should certainly jump in and both replicate this quick look and delve into other aspects of James’ hypothesis. But, for now, the initial evidence doesn’t appear to support the injury risk claim.
Great stuff. This is the way it's supposed to work: Somebody throws out a theory with (ideally) some evidence, and somebody else tests the theory. Petti acknowledges that this test wasn't comprehensive, but I think it's one hell of a start. One thing I would like to see is more historical data; thanks to Retrosheet, we have ground-ball data going back for some decades. I would like to see a study that includes Randy Jones and Mark Fidrych, which isn't to say I think the results will be any different.