[1] He made his Torneo Descentralizado league debut in round 2 at home against Alianza Lima.
[2] Manager Roberto Mosquera put Santillán in late in the match for Javier Chumpitaz, but in the end his side lost 1–2.
[2] In his fourth match, he made his first league start, playing the entire game in the 1–4 defeat to CD Universidad San Martin.
[3] He finished his debut season in the top-flight with nine league appearances,[1] but with his team being relegated.
In January 2012, Santillán joined newly promoted side Real Garcilaso, where he was given the number 27 jersey and was expected to compete with Hugo Ángeles for a spot in the starting XI.