He would have been useful for the Sox, but losing him didn't hurt them really. His 23.4 bWAR isn't top 400 all time. To be top 300, you need 30 bWAR. Guys with 30 bWAR: Woody Williams, Teddy Higuera, James Shields, Mike Boddicker, Brandon Webb, Andy Benes, Barry Zito, Sid Fernandez, Rick Sutcliffe, Charlie Leibrandt, Freddy Garcia, Chris Carpenter, John Tudor, Dan Haren, José Rijo, etc. A lot of guys with either really high peaks (ex. Higuera) or generally long productive careers (ex. Sutcliffe). Those are lots of good pitchers, but guys you wouldn't be saving the baseball cards of. Arroyo is down with the likes of Ken Hill and Bill Gullickson, guys you need to be reminded once played the game.