Under Armour showed up at the perfect time to make a pitch that would make him one of the most recognizable athletes in the world. They offered him $4 million to join their team but Nike still had the rights to match their offer.
You have to understand that Under Armour was still taking a huge risk in betting $4 million on Curry. Up to that point, Curry had failed to reach the playoffs with the Warriors for 3 straight years and only played 26 games the year before due to injury. He was always looked at as injury-prone. It was a huge gamble..