 McCarthy akabatana neLeinsters provincial rivals Munster pachibvumirano chemakore maviri mushure mekupedzwa kwemwaka wa2018-19 mwaka, uye akaita kukwikwidza kwake kwekutanga mudunhu mukutanga kwavo 2019-20 Pro14 39-9 kukunda vachipesana neWelsh side Dragons musi wa28 Gunyana 2019. Mutambo wake wekupedzisira wepurovhinzi yaive mukukunda kwavo 5411 kure neZebre mumutambo wechitanhatu wePro14 Rainbow Cupmusi wa11 Chikumi 2021. 