dunno is the concise answer and i own both. i've long since benched uggla (in my main league; i drafted michael young for just such an occasion)...with an eye toward the fact that he may not produce all year long. or maybe the 20th of august he'll go off. he is frustrating though, i know that. Funny almost stat quirk i picked up on a week or so back though:5ish? of his home runs are in the eighth inning while only 3ish are earlier...4th twice and 6th once i believe this year...don't know what it's worth, but there. and like Hootie says,"you can call me a fool"?; he's got a good deal now in the A T L and it may make him fat.
Joyce on the other hand, i picked up when Hamilton went on the DL and i soon aquired him in all four of my leagues. i'm reluctant to move him as i've read that he and his hitting coach has tweeked his mechanics (something to do with a leg kick for timing purposes) and while that's not so evident to me, he is hitting lefty's well...historically not his strong suit. That and the daily daily's are just too good. i'm a rbi junkie and he keeps bringing the good stuff, so why quit?
i say stay where you're at...even though i think joyce should regress, i don't know if he will, seeing as no one really knows...wouldn't people have said the same thing about bautista last year, and things like that...ya never know..and I just don't like Uggla right now..I don't see things getting that much better for him...should he turn it around? yes. but will he? who knows, and I say its's not worth it..like the other response said, try for something more! Hope that helps!