A couple of other Arroyo observations that are interesting:
1. An awful lot of the damage that Arroyo gave up was very late in his outings - after the 90-pitch mark. The Red Sox bullpen was awful for most of the season last year, and Francona has a very slow hook. So he got left out there an inning too long on many occasions (as did Matt Clement, so in reality, he pitched overall much better than his ERA indicates. I'm not familiar enough with Narron to know his hook tendencies, but I would say that its fairly important to get him out of the game when he starts to break down for maximum success.
2. He gives an awful lot of the credit for his resurgence in Boston after wearing his welcome out in Pittsburgh to catcher Jason Varitek. I'm not sure how much of that is really true, but the fact that he said it and apparently believes it would indicate that he is very catcher-sensitive - that he needs a good relationship with his catcher. Arroyo throws a variety of breaking stuff and mixes in a decent fastball and so-so change, and generally has real good location. With that kind of repertoire, its important to work the hitters together as a pitcher-catcher team. I see that Larue's reputation for game calling isn't all that good, but they could work together and make something good happen.
3. Arroyo's not quite as much of an extreme fly ball pitcher as it seems. He actually fluctuates from game to game, and it depends on which pitch is working. When his curveball is working well, he induces lots of lazy fly balls, but most of his other pitches (slider, fastball, change) are down in the zone, so its his curve that most often induces fly outs (and home runs). If everything is working, he uses his curve primarily against righties, then switches to the other pitches against lefties. I think its fair to say that he will have much less of a problem with righties in the N.L. than he did in Boston, because a good chunk of the doubles they hit against him in Boston will be F-7's in the N.L., but he still is going to need to work hard to get lefties out.
4. One of the problems Reds pitchers face in the N.L. Central isn't so much pitching half their games in the GABP, its having to pitch a big chunk of their away games in other hitter-friendly ballparks like Wrigley, Miller, PNC and Minute Maid. The one saving grace for Arroyo in the other parks is that they seem to all favor right-handed hitters, so he should be okay. Maybe if he pitches the day after Milton or Williams, the righties will be tired out after pounding them the night before.
Seriously, I think you guys are going to end up loving Arroyo over there. I don't think he's the type of pitcher who is going to put you over the top, but he's a good containment pitcher (doesn't lose his cool after giving up a big hit) and will keep the Reds in ballgames long enough to let your bats take charge. If Harang and Claussen continue to pitch well, and one of your young guys comes up big later in the season, things could pan out well.