Provided is a catalyst system for producing a polyolefin blend, which catalyst system comprises a mixture including the following catalyst components: i) a catalyst component A capable of producing an isotactic olefin polymer, and/or a catalyst component A' capable of producing a polymer comprising an isotactic polyolefin block; and ii) a catalyst component B capable of producing a syndiotactic polyolefin, and/or a catalyst component B' capable of producing a polymer comprising a syndiotactic polyolefin block; wherein each of the components in the catalyst system is distinct from the other components in the catalyst system.