i'm "proficient" at every position, it's just that when i play and get to choose what i play i'll always choose something easy for me to play and end up not getting to practice anything else so when the meta shifts i'm completely "out of date" - ie i got bored of top lane end of season 2, started playing mid and bot more, basically never played top, ended up like 2 months behind on current-meta champs when i was forced into top lane again and lost super hard because forget me the lane changed so much
just my opinion i guess