I would not personally give up Lacy and Sankey for him. yeah he is coming off a 3 TD game . but the 2 weeks before that he only had 3 catches a game and people were not even sure if they wanted to start him this week. I had quite a few people ask me this week if they should even start Sanders. I told them yes. if it aint broke don't fix it. I tell you this so you understand I say this not because I do not care about Sanders. I say it because you do not give up 2 starting RB's for a WR. I understand Sankey has not done much , heck I don't even like him. but he is the starting back and starting backs who are getting the touches he has gotten over the last couple weeks will eventually have that game. and Lacy has become relevant again. then on top of that you have Antonio Brown,Mike Wallace and Michael Floyd who are solid..
Sanders would look nice when looking at your starting lineup. but staring at your bench will be ugly. and without a bench you cannot win.you will be counting on Jennings to take over the job like before but Williams will still get his carrie. how well a 3rd back Jennings will make is the real question for me.then you cannot tell me as a McCoy owner that he is the same runner he was last year. hopefully after this bye he will show the footwoork he had last year and will quit falling when the wind blows. Ball has IMO lost his job to Hillman. so you are still not sure how your RB's are gonna shake out. and having a 3rd back is the 3rd most important thing to have. WR's are dime a dozen. this trade would help him alot more than it would help you as he needs RB's in horrible way. you do not need WR's in a horrible way. plus you mke the deal and you lose a game because Sanders has already played.
Also, I expect my Lions to slack off in defense this year. I love them but Brees showed our weakness and I am afraid the league will take notice. our secondary can be lit up. as high as Detroit is ranked on defense if they were dropped today I would not pick them up.
I would keep my depth at RB as the season is long. now maybe if you got him to throw in McFadden instead of the Lions defense that would be something I would do.keep your RB depth that way. especially since I think McFadden blows up this week.
Now this is just my opinion, I am sure there will be many that disagree with me and I hope they post here so you can see both sides of the thought process which will help you make a objective thought out decision.