Do you think Overwatch has made Bastion too powerful? The good news is that yes, Jeff Kaplan agrees with you, as he’s outright said that the team balanced him to be a bit too powerful right now. But the key word is “just a bit,” as Kaplan’s post is more about the nature of balancing a game and the perceived metagame vs. the actual metagame seen by developers at all levels.
Kaplan explains that when a hero is underpicked, that sometimes doesn’t mean that hero is underpowered; Mercy isn’t a frequent pick, for example, but she’s among the top five most powerful heroes in high-end play. Getting players to pick a hero more often often requires tuning up that hero, and that always makes the hero seem overpowered, because you’re going from almost never seeing that hero in action to seeing them constantly, along with a new power buff. This doesn’t necessarily mean the hero is overpowered, just that players need to adapt and see new strategies in action. The full post is well worth a read even if you’re not very into Overwatch, as the philosophies are applicable for any game with multiple choices for players.