Papelbon did have 3 or so starts in the ML the season prior to last, in which he held the Angels and others to 2 runs in I believe 5 innings each outing. However, that by no means is a track record, and I believe that his 3rd and 4th pitches will make or break him.
Also, Gom, I'm not so sure Matsuzaka will struggle. I mean he has 4 MLB caliber pitches, will pitch a lot less than he did in Japan, does well in the spotlight, and he is already used to having the game called by his catcher (so Tek will have total control, and that usually fares well).
So basically you have a catcher who knwos the league better than anyone, a pitcher cocky anough to get through it, and a solid arsenal of pitches to unleash on hitters.