Is this a good trade in fantasy baseball?

I would not make that trade. Longoria is the best 3B in the AL, and he plays on a team that's capable of scoring a lot of runs. Pedroia is top notch at a position with few great players, and a Front line pitcher is always valuable on any team. Although I like Reynolds, I've had him in seasons past, and he will sink your teams average. Hanley and Vlad are too injury prone to rely on playing everyday in my opinion. Your safest and best bet would be to keep what you have. Good luck