To me it looks like you have enough pitching, so I'll evaluate this deal on who I think is the better player of the two. It's close, so if you really think that you need pitching, I'd have no problem with you making it.
It's an interesting comparison between these two guys. Each have been pretty volatile in their careers and this season. However, I like Panda better. As a fairly quantifiable comparison, I'd probably draft Panda a few rounds, maybe 3, ahead of Gallardo if there were a redraft today. Panda's stats are all pretty stable with a babip around normal for him, customary very low K-rate, and a bb-rate that could actually improve. On the other hand, Gallardo has some pretty big red flags. His FIP and xFIP point to him being a pitcher with around an era of 4. The K rate is still great, but his major issue has been that he reverted to his problem of the past: walks. His success last year was predicated upon the lowest bb-rate of his career, but thus far it's been way up... almost 1.5 more per game compared to last year (though he has been better in June). Additionally, his fastball is a tick slower this season, dropping by .8 MPH, a pretty significant drop.
At this point, Gallardo is a high risk/ high reward type of guy. I'm not sure it makes to deal an excellent hitter for that. You could probably get a better pitcher. I do like the idea of dropping Moss for Shark, though.
Please help with mine:viewtopic.php?t=449046