Complex sentence: Cornelio was a talented musician and considered a legend, but he had been much more popular with Los Relampagos del Norte than he had been as a new solo mariachi singer, proving that Ramon's management of the group and contacts were phenomenal and unsurpassable.
Split into simpler sentences: Cornelio was a super talented musician and considered a legend, but he had been much more popular with Los Relampagos Del Norte than he had been as a new solo mariachi singer. Again proving that Ramon's management of the group and contacts were fenominal and unsurpassable.