No, Gordon has proved himself this year, moose has proved nothign yet. So, I wouldn't replace him. If you want to take a chance on him then I'd drop Tomlin for him. Although your team looks pretty good, I think you can afford to drop Tomlin with your pitching staff. Then hope Moose tears it up and trade him or Gordon quick.
3B is a thin position ... so you don't replace a solid 3B with an unproven rook. But I'm all about picking up highly regarded rooks this time of the year... they have a limitless ceiling and if they don't work out you just throw them back. Dropping Porcello makes sense. He's having a decent year ratio-wise, but he isn't really dominating anyone. I expect him to see a correction.