First of all, if you assume the results for 7th, 8th, and 9th are independent, the number is closer to 34% of the time than 35%. I am not sure this is significant -- I was using rough numbers Second, those outcomes aren't independent--big innings are more likely to be followed by big innings than would be expected by random, so it would be less frequent than that. I cannot understand the point you are making here. Third, if my pen is giving up 2 or more runs per 3 innings in less than (probably) 30% of the games, that's really not bad. The other assumption I made is that they are giving up 2 runs, yet finishing the IP -- in reality they would not be able to get three outs on average. I am quite certain that if you had 3 Derrick Turnbow 2007 clones working in the BP, 7th 8th and 9th -- that ERA would be over 5.