The difference between the two leagues is usually not more than one-quarter of a run. Would pitching in the AL East further skew this difference? Yes, it would, but the offenses in AL East, other than the yanks or Sox, were not quite so powerful prior to the last 2 seasons. In 2006 and 2007, other than the Yanks and the Sox, the other teams were not juggernauts. One thing you don't factor in is that if he played on the Sox, he wouldn't have to face them at all. Other AL East pitchers face the Sox and Yankees about 4 times each in a season. Not having to face the 2006-2010 Sox 4 or 5 times each season would have been a huge thing. The orioles, Jays and Rays have not been consistently great from an offensive standpoint. Arroyo is a good starter. If he pitched in Safeco or Detroit, his results would be even better.
You got entrenched in this argument by you jumping in on the side of RedSox Rules who just made an asinine remark about the Arroyo/Pena trade by saying that both suck. One sucks. The other is a good major league pitcher who will hit 100 victories this season. Now, don't swallow your tongue about victories not being a good measure of a pitchers value. I am not saying that, but guys who reliably take their turns for several years have a tendency to build up some wins. Guys who are not good and reliable never get that opportunity. Someone once said that you have to be pretty good to lose 20 games in a season. It sounds ridiculous, but it is true. A major league pitcher that gets to 100 victories clearly had something going for himself. As steady as Arroyo has been he could get 150-200 wins. That's not a suckbag. Wily Mo Pena was and is a suckbag. That wasn't just somewhat of a bad trade. It was a terrible one. The FO has acknowledged its mistake. I don't know why posters will not acknowledge how bad it was The fact that Arroyo is not Josh Beckett or Sandy Koufax doesn't make the trade any less bad.