What's probably going to happen if you put a small detachment on somebodies flank, is that he's going to kill them in one turn to deny you that combat rez... Unless of course you're facing some lowly skaven or beastmen or statetroops or whatever equivalent you can find, but any hard hitting unit with multiple attacks will slaughter them.
As Derek here says, if you take small detachments, use them as redirectors. Plus Archers, being skirmishers, will probably stay alive a little longer.
I wonder if archers still give hard cover to your statetroops behind them, though?