Ugh, that is tough. It is always tough to be the one who squashes a trade.
Trades are all about filling needs. Based on the pitchers that you listed, the guy doesn't have a true #1 starter. He has some good pitchers, but no Maddux, Mussina, Clemens, Pedro, etc. Lowe is his best pitcher so far, but he is still only one month into his first year as a starter since he entered the pros with the Mariners.
Had the outfielder been someone who doesn't have a great injury risk, then I might tell you to worry. However, I see this trade as both teams taking a risk. Dye has only been back for a short period of time with only 1 HR thus far. Duckworth, in my opinion, is a pitcher that will reach Kerry Wood status. Great stuff, strikes out a ton when he is on, but has control problems from time to time.
As for Williams, he did win 15 games last year and he plays for a proven team that, when healthy, will win games.
So after all of that, I wouldn't be concerned about this trade. Both owners are taking a risk with this one. Actually, if Duckworth works out his control problems and Williams comes back healthy to finish the year, the team getting those two might have a slight advantage over the team getting Dye.