Re: Shelby Miller vs. Tyler Skaggs?
How many keepers are you allowed? If it is just a few I would drop Skaggs or Miller, whichever one doesn't get a rotation slot to start the season. Likely neither of them will. I think Miller is more likely to be a star pitcher eventually, but not this year. So I doubt he would be one of your keepers next year.
I would try to trade Uggla before dropping him. He has some trade value. Not a lot, but some. He is good in 3 of the 5 hitting categories. I wouldn't drop him.
I am not a believer in Fowler, so I think you need two outfielders. I would try to trade Broxton and Frieri to fill your hitting slots because their closer roles are in jeopardy.