Stimmed marines

  (Edited: )

Should counter pretty much all skytoss. If all he's doing is air, there's really no need for anything more than that, especially at the silver level.

Speaking of which, if you're silver, I guarantee all you need is *not* better positioning and map control. It's better macro. Good macro will take you all the way to diamond, even if all you do is 1a. Perfect macro will take you all the way to low masters. So work on your macro first. Positioning and map control sound important, but I guarantee they are not a silver leaguer's lowest hanging fruit.