The award was never for the best player on the winning team, it was always about contextual performance within the finals. Steph played mediocre by his standards whereas LeBron was far and away the best player there. But Iggy flipped the script and was the deciding factor, which is why he deserved it
Narratives matter—you can just look at the stats if you want to decide who’s better in a vacuum but that’s never been the purpose of these awards. Giving it to LeBron would have been a shitshow for obvious reason, they’d probably still be arguing about it on TV. Giving it to Steph would have been undeserved since he didn’t have a great series and disrespectful to how great LeBron was. But even that aside, Iguodala, despite not being the best player, stepped up and won the Warriors the finals. That’s as valuable as you can get