Yes. Patton is MBT and not Medium Tank.
1. When did the term 'Main Battle Tank' emerges and when did the 'transitions' from Medium Tank to MBT takes place? i.e. In AFV inventory lists, i did play Steel Panthers II (and 'remake') before, originally in purchase screen the vehicles (M48 and M60 respectively) are classified as 'Medium Tank'.
So in game terms. only less than 20 turns apart that Medium Tanks phased out in favor of MBT. So to make the two different units relevance in game. in addition to 'tech upgrades'. When should Medium Tank to shows up? (1930? right after Vickers released 6 ton Mark E and Mark F 'light tank', (which were made for exports)? (which its designs and performaces were actually forefathers to Medium Tanks, able to move significantly faster than WW1 tracked AFVs and having a decent cannon that can fight any land units by that time). What is the first 'medium tank' that's developed or released right after Vickers export?
2. Did 'American' armor doctrines really good particularly under George S. Patton himself? should 'Cavalry Tank' be Mediumtank replacements for Americans? because they were the first to fully reorganized cavalry as fully tank units while someone else maintained 'cavalry' as horse units either as lancers or 'mounted infantry'.
Quick and dirty guide to American Armor and the MBT.
The first two Main Battle Tanks were the US M60, standardized in 1959 and in production by 1960 and the Soviet T-64 that went into service in 1964. As stated, both of them were quantum leaps in armor protection (the T-64 had some of the first plastic/steel composite armor used anywhere and the M-60A1 added Kevlar to its 300+mm thick turret armor), firepower, and mobility. Officially, the term Main Battle Tank was not adopted by the US Army until 1963, when the last of the old M103 heavy tanks were retired, but the term was in general use since the end of the 1950s and is now specifically applied to the M60, T-64 and most subsequent tanks built since 1965.
Medium Tank has a number of definitions, frequently only referring to the weight of the vehicle, which is immaterial and simply a by-product of the important measures of performance. So, for example, the German PzKpfw IV was originally classified as a Heavy Tank because it was supposed to support the PzKpfw III Medium Tanks with high explosive fire when it was introduced in 1937. But in fact, it weighed just a little over 20 tons, so by the standards of 1941 and later it was barely a Medium Tank by weight.
What makes a tank effectively a Medium Tank is that it is armed with a main gun that can fire both effective antitank projectiles and a decent high explosive projectile. Thus, it is effective against armored and unarmored targets. Combined with a speed 3 times faster than a running man (30 kph or better), and it can outshoot or out maneuver anything else on the battlefield - in theory.
So, the Vickers tanks were effectively Light Tanks or Infantry Support tanks - heavy on the machineguns, but mounting only a 47mm gun which might be effective against 1930s tanks, but had a mediocre high explosive round (2.5 kilograms weight). The German PzKpfw IV or the Soviet T-28 were arguably the first Medium Tanks, both designed in 1933 - 34 and both carrying a medium-velocity 75mm or 76mm cannon (10 kilogram weight High Explosive shells). By 1942 the German PzKpfw IV with a high velocity 75mm cannon, the T-34 with a high velocity 76mm, and the US M4 Sherman with a 75mm cannon, were all in the Medium Tank category and all served in that capacity for the rest of the war.
The US Army after WWI officially assigned all tanks to the Infantry Branch. The Cavalry were not officially allowed to have, develop, or play with tanks at all, so instead they developed 'combat cars': which were fully tracked light tanks by another name. The M2, M3 and M5 series were all very fast (70 kph or better, about 50% faster than the average Medium Tank) but mounted only a 37mm cannon and, originally, up to 5 machineguns. They were classic 'cavalry tanks' in fact, but in 1940 when the Armor Branch was established in the US Army the Cavalry Branch refused to give up their horses and so ceased to have any effect on the development of US armor or armored units. (Their horses disappeared anyway, since most US Cavalry formations in WWII were Mechanized Cavalry with armored cars, armored half-tracks, jeeps and light tanks but for Historical Trivia fanatics, the last mounted cavalry charge by US horsemen was made by a mounted scout troop of the 10th Mountain Division in April 1945 just a week before the war ended in Europe!)
George Patton also had very little effect on US Army armor development. He simply followed the adopted doctrine very well. The US doctrine was that Armored Divisions were for exploitation and pursuit but not assault operations, so he never backed equipping US tankers with heavier and more effective tanks with better anti-tank capabilities. Basically, he was a very good horse cavalryman who understood the classic cavalry actions of pursuit, envelop, and screen and transitioned very well to using mechanized forces for those tasks, but never appreciated the capabilities of a balanced armored formation for assault operations the way the German Panzer Division was used.