I think any Reds fan who's been paying attention for the past decade would tell you that Reds pitching prospects get hurt at a ridiculous rate. Well, now we can say this for sure:
The Mariners suffer more serious arm injuries than other major league teams. This is indisputable. From Ryan Anderson's multiple shoulder issues to Jorge Campillo's one-inning debut-and-shutdown ("Hello!" "Goodbye!") we've seen the Mariner system decimated in recent years. This is not a perception issue that's a result of being too close to the problem.
For this work, I looked at every team's pitching prospects, as ranked by Baseball America, from 1995-2004, and attempted to find which prospects had serious arm or shoulder injuries requiring surgery that cost them a year of playing time. You can read the methodology notes, or go to the index page for links to all the team pages.
In absolute terms, the Mariners tied with the Reds with nine serious injuries. As a percentage of prospects, they were tied with the Brewers for second place with 32%. The average team was at 20%. Standard deviation was 2.4 (8%).
Truly great work here by U.S.S. Mariner.
The Reds had 25 ranked pitching prospects in the years examined. Nine of them lost more than a year to injury, with seven of them suffering shoulder injuries and two of them suffering elbow maladies.
The seven shoulder injuries was easily the most. A few teams had five, but many had 0-3.
I looked at "expected injury rate", figuring that 1/5th of the pitchers would get injured. The Mariners were four pitchers above that, along with the Reds, with the Brewers at three. You would expect the A's to have six pitchers go down during this period. They had none.
Very interesting stuff, and I'll have more on this soon.