Few things to consider when picking off meta

1. Compare your pick not to the same champion in other roles, but other champions in the same roles. If you're thinking about Sion support, it's pointless to compare whether Sion is better top, jungle, or support. What's important is whether Sion support is better than other supports. Who else has a knockup, shield, slow, and armor shred? Zoning? Harass? How is his pre-6 engage? Does his post-6 engage justify picking Sion over other picks? Is Sion good in this matchup? How is the team synergy? Which brings to the next point...

2. What does your team need? It doesn't matter if you're a god at AP Ezreal support, if your team has nobody to peel for the carries. This isn't specific to off meta picks, but being off meta is no justification for picking someone bad for your team's composition.

3. How's the matchup? TF top can be OP if you can kite enemy top laners and stop them from engaging, but if the enemy has someone with good gapcloser or untargetability, your only strength is now nullified. Know the matchup, and don't counterpick yourself.

4. Do the research Can this champion function in a given role? What items would support this playstyle? This includes something like trinket (red if you need to ambush a lot, yellow if you're more supportive and/or safe, blue if you have little to no escapes), which big AD or AP items you need, how much into mana you need to itemize, or any items that synergize extremely well.

I like off meta picks and would love to see more off meta picks succeed (and become meta, unfortunately). But there are things to consider if you're trying to have a successful off meta pick. Please consider these points when picking off meta. Also, share your tips and/or favorite off meta picks in the comments!