Complex sentence: This would be Holmes' last appearance for the senior team and he proved to be an instrumental part of the reserve team playing right back for the majority of the season, but even slotting in to centre back and sometimes even left back.
Split into simpler sentences: This would be Holmes' last appearance for the senior team. He proved to be an instrumental part of the reserve team playing right back for the majority of the season, but even slotting in to centre back and sometimes even left back.