My friend basically did this with Ezreal. He'd been losing a bunch, started playing Ezreal, kept losing, asked me for tips and I played a game with him with EVERY. SINGLE. SUPPORT. and told him what to look for each support doing, what a not-so-skilled player on that support might do instead, and how to play with that. And of course, how enemy matchups went as well. About 8 supports in he started doing really well, then I see in his match history he'd built things like Shiv and Duskblade and I told him not to buy those, he played two more games normally and then just gave him up for Sivir and fed his ass off from Silver 2 down to Silver 5. I will never understand that man.