Kevin Millwood against Boston on 6/21: 6IP 6ER
Kevin Millwood against Boston on 6/27: 6IP 0ER
Bronson Arroyo against Cleveland on 6/21: 7IP 1ER
Bronson Arroyo against Cleveland on 6/27: 6.2IP 5ER
As soon as I read this theory it made me think of how different the stats were for Arroyo and Millwood in their last starts.
Just two cases though, so it hardly disproves anything. In general though, I'm not sure where one would go to look for such stats...