I don't see Alzare as replacing Caicedo either, but I do see him playing that role in the games that Caicedo / his replacement doesn't play.
According to Wyscout data, Alzate has a very similar profile to Caicedo:
Alzate and Sarmiento play completely different positions, so I don’t think they’re related at all. Alzate is a deep lying central midfielder and Sarmiento is an attacking midfielder/winger.