Arroyo recently signed a contract that was slightly below market value because he wanted to be a Red Sox. Of course, that contract made him a more valuable player in a trade and sure enough he was traded. The lesson learned - if you give a hometown discount be sure to add a salary kicker or a no-trade clause to the contract.
Wily Mo Pena brings a lot of power to the Red Sox, although those HRs come with a lot of strikeouts and he's had problems with injuries in the past. With a full OF already it's hard to see how Pena will get regular playing time unless they plan on playing Ortiz at 1B or there's an injury to an OF.
I hate the move, but that's more because I already drafted Pena in an NL only league than anything else.