My mmr is 4.5k and i have some experience with being a captain for a few small tournaments. My role is pos 1 or 2 (mid or carry) but i can easily switch to other roles since i adapt quite easily and ive already played all the roles.
---- Top heroes for each role ----
Mid- meepo, invo , tinker , wr , sf
Carry - meepo, ls , am , jug , void
Support(pos 5) - daz,kotl,omni,cm
Roam(pos 4) - rubik, ns , bm , es(spirit and shaker) , lion
Offlane - void,timber,bm,sniper,zeus