When Overwatch was released one of the more interesting questions was whether it would be better to have mostly flex players or a group of specialists who are the best at what they do. The idea of the flex players was that even though they weren’t the single best at any particular hero, they’d be much more resilient to patch/meta changes. On the other hand, the specialists would be even better in particular patches that favored their types of characters, but then fall off and struggle should the game shift away from them.
After watching Overwatch for a bit (there haven’t been any LANs so this isn’t that strong of a conclusion), I think it’s better to have a team of specialists. Not a one-trick player who can only play one character at the top level, but someone who specializes in groups of characters. The reason I think this is because subbing players in and out of Overwatch seems to have a much less drastic effect on overall team synergy when compared to other games like Dota 2, League of Legends or Counter-Strike. In which case having a good bench is better than having a bunch of flex players who switch their heroes. On top of that, the ecosystem of Overwatch is such that I think players would rather be subs on Overwatch League teams than main players on non-OWL teams. That kind of incentive doesn’t exist in other esports unless you are a lesser player.