For some reason, this weekend I was thinking about the rule of 30. This is the rule with young pitchers that if you increase their workload from one season to the next by more than 30 innings, you are putting them at high risk for injury. You saw this play out most famously with Kerry Wood and Mark Prior for the Cubs. Two promising young starters, one of which is now in our minor league system hoping to stay healthy and get a call up. The problem I have is that I couldn't help notice that pitchers in the past would regularly increase their workload and not suffer the same problems. For example, Bob Gibson threw 75.2 innings his rookie year, then 86.2 the following year. That number jumped to 211.1 the following season, which would blow away the rule of 30, but you don't see Gibson fall apart. The next 5 seasons after that he doesn't pitch less than 233 innings. Warren Spahn threw 125.2 innings after taking a three year hiatus, I assume for the war. He then threw 289.2 the next season. Again you don't see him fall apart. He throws 257 innings the following year, 302.1 the next year, and goes on for another 12 seasons pitching at least 245.2 innings in each one. Mel Stottlemyre went from 96 innings in '64 to 291 innings in '65. Again, no break down. Now I know there are exceptions to every rule, but the more starters I look at from that era, the more you see the rule of 30 not applying.
One thing I did notice however was that the average age of these starters their first season was about 23 or 24, where as Kerry Wood, and Mark Prior were about 21 and 22 respectively. I wonder if its trying to rush these high school and college kids through the system that makes the rule of 30 true. Otherwise I have no idea how to account for increasing workloads by 100 innings for pitchers in the 60's and not seeing the rule of 30 take any effect. What do you all think?