I would take the trade. Having Johnson and McCoy at RB would be an unbeatable combo most wks. It has upside if Rice can come back and produce and with Moss gone he should be good as gold.
You give up value in Lloyd but he is starting to look like a sell high candidate as Denver seems to get worse from week to week.
D Williams and B Jacobs are pretty much useless now anyway so it is great that you can get the value of McCoy for them.
Unless you are in a PPR league Welker is no more than an emergency fill in but you still have good value at WR and McCoy gives you great value at RB.
who are your starters and whats the format? A little trickier to answer without this.
But overall, I like McCoy the most in this trade, I would give up your 3 guys just to get him alone in most cases.
Welker is crapping the bed, and I am no where near as high as Rice as some people here, but who cares if your getting McCoy.
Only problem could be lineup; if you start 2 RBs but 3 WRs, then I dont do it, since the upgrade from Charles to McCoy is not as big as your downgrade from Lloyd to Welker/Rice.
This is where I 100% disagree with Deacon, Lloyd had 150+ yards just last week. He is a massive stud at WR, no matter what is happening in Denver around him.