It's a huge jump to get set and when he finally does, the ball is half way to him and his feet are too wide for him to step towards the ball. All he can do is roll backwards, which is what he does. If he is in time with the shot and in a position to actually move towards the ball, he can make the save instead of stare at the ball hitting the net. A very similar situation happens on the next goal.

There's more to say about Castaño. His wide stance kills his lateral movement and his post-to-post time is slow. He opens up his five-hole too much. (He's megged in the Wilmington game, video above, as well as Richmond fairly easily.) He is on his heels far too often. His 1v1 approach is wild and not intended to play percentages while utilizing some hybrid of a crab stance while he waits for players to get closer (see red card in Wilmington game). He's not particularly great in the air. He also is very reluctant to use his right foot for distribution.

Conclusion

Cody Cropper has shown us how hard it is to develop with bad mechanics. Can it be done? Sure, but it's not likely. For Castaño to continue to grow, he needs to revamp his entire approach to the game. His time with the USYNT means nothing. Several goalkeepers have gone through the USYNT scene only to amount to journeymen backups and that's the path Castaño is on if something doesn't change soon. While twenty sounds young, he has been playing a certain way for some time now. He is becoming less moldable and some of his peers - sophomores in college - are already ahead of him.