By the time Patton and others realized that The Sherman was'nt going to br successful on the battlefield it was a bit late to change things , They agreed that the next tank should be a diesel but the logistics of handling two fuels to the battle area would be too difficult they felt so they were stuck with a gasoline powered tank for the duration of the war , yes they had built a small number of Stuarts and Shermans with diesel engines but kept them for training purposes state side only .
Your right in that they felt numbers ,training ,battle field recovery and repair would make up for the tank design flaws.
imo.