Complex sentence: Richardson's resignation was simultaneous with that of his brother Jon, who had been president of Bank of America Stadium, and both were considered unexpected moves as the two had been expected to eventually take over the team from their father.
Split into simpler sentences: Richardson's resignation was simultaneous with that of his brother Jon, who had been president of Bank of America Stadium. Their resignations were considered unexpected moves as they had been expected to eventually take over the team from their father.