Rice is a superior leader on the pitch. Reckon if we'd had Rice around at the start of April last season, we would've been much harder to break down and wouldn't have tossed away so many points while getting bullied through the centre.
Our senior players Partey, Xhaka, Zinchenko, Ramsdale all went missing to a great extent during that precipitous April downturn, fatigued, mentally overwhelmed, or injured.
Partey was available for the whole period, so it's not injuries that are a challenge with him. It is very unclear that switching Rice–Havertz for Partey–Rice in those 6–8 roles would help us under greater pressure, and Arteta's mad scientist use of Partey at right back would be a major setback.