Alemán made his professional debut with Deportivo Saprissa where he was known for his hard work on the field, his quickness, scoring skills and most of all his talent for creating assists.
5 days before the transfer window closed, Aleman signed with Liberia Mia, but was allowed to play 2 more matches with Puntarenas against Saprissa, one of them for the UNCAF Cup Semifinals.
Alemán participated in the 2005 FIFA Club World Championship Toyota Cup with his team, who ended up in third place, behind São Paulo Futebol Clube and Liverpool F.C.
[5] On 23 July 2014, Alemán transferred to China League One side Xinjiang Tianshan Leopard.
[9] Alemán has made ten appearances for the senior Costa Rica national football team, his debut coming in a friendly against Chile on 2 June 2007.