Boost archer damage by 100+%, give them -66% of their running speed, make every map open plains. Enjoy shieldwalls and stuff, because random herpderpcharge team dies.
Right now, with half the map being worthless run to clusterfuck maps, and on even normal maps tactics being of little consequence b/c the team which does use tactics still won't prevail over the stacked team, and stacked team has no need for tactics because they win anyway, well... that's what you get.
Alternatively, old money/xp system so you get money/xp for kills scored in your proximity.
Actually, just make every map random open plains. Perhaps tweak in for an occasional ruin/etc also random. The only way to force people to cooperate is when failure to do so gets them killed repeatedly in idiotic ways.