The Sherman was deployed and the Pershing delayed for the simple reason of economics, by, of course, the War Production Board. The Sherman was fast, cheap, and easy to manufacture. The idea that the Allies got only the best weapons is completely false. Often, therest of the Allies relied on the Russian position that quantity has a quality all its own. A lot of weapons were chosen on the basis of cost and ease of manufacture.
The main reason for a tank back then was NOT to engage enemy tanks, but rather to support infantry in attacking infantry and fortified positions. Tank destroyers, ike the Hellcat, ere intended to take on tanks by using speed, maneuverability, and a large gun specifically intended and designed for use against heavy armored vehicles. Tanks were not made tough to just to fight other anks, but to survive being attacked by tank destroyers and artillery.
Patton knew all along the Sherman was outclassed, and would have preferred the Pershing had he been able to get them. His tactic of bypassing enemy armor was developed because he could ill afford to take them on if he could avoid it. He would have still preferred to bypass them if possible, but he would not have been forced to do so if he'd had plenty of Pershings and Hellcats to take on Panzers and Tigers with. Only a fool would prefer the Sherman over the Pershing, and only a fool would attack Tigers nad Panzers head on with Shermans if he could avoid them. Patton was no fool. And he despised wasting men and equipment.
