Lets also remember that the upgraded Shermans and tank destroyers didn't perform too well against the German armour. The only tanks they had that were effective was the Firefly and Pershing.
In terms of what? Long barreled Shermans could easily knock out basic German hanks under half a mile distance (theoretically speaking, and practically quite far from impossible). Yes, basic tanks, ranging from PzIV to StuGs and some Marders and such and such and such. Panther is a diffrent story. Jagdpanther is also. Tiger might be also. But hey, Tiger's a heavy tank, Panther was a "heavy tank" based on German classification system back then and bla bla bla.
So theoretically speaking, allied tank destroyers had quite good chances to disable basic german tanks and even some other "special" ones in some circumstance. Yes, allied tanks sucked considering their armour and such, but I guess that also means they lacked firepower, usability, number built and issued also. Not to mention US doctrines different greatly from German ones.
And yes, as damm great tank Tiger might have been, or Panther as how godly it might have been, let's take into account few things, shall we?
First, by the end of the war German industry was being bombed repeatedly. And again. And again. And again. That will cripple the production more or less.
Second, considering the material problems (like the amount of Ersatz gear germans used in the end of the war), the steel quality or whatever they used might not have been that great or may vary more or less.
Third, let's take Tiger as an example. It does have nice armour, it has nice firepower in terms of AT capability and has great range. But what, approximitely 1200 built only between '42 - '45. Compare that to about 20.000 M4 Shermans built alone in '43.
So yes, while Americans did suffer with some problems in terms of firepower, it is very diffrent thing to engage a common\light tank vs common tank than common\light tank tank vs heavy tank. Even Stuart could beat PzIV's long barreled versions in short range. Even at longer ranges it might stand a chance if the crew knows where to shoot.
And yes, even a short-barreled Sherman might be able to that. And long barreled - no problem. Unless if the shell had production malfunctions, squirrels shamans did their unlucky dance, PzIV crew had good luck or whatever else you can imagine as possibility. If they were extra lucky, it might have just made a hole but the tank is still entirely functional.
Problem of the ever-lasting "tanks are unrealistic" discussion? The fact we have way too simple and small scaled game to have realistic armour system enough to be worth the drama and hassle. We all know X can penetrate Y and such, but how about if we have LARGE scaled map (Orel is not one in this purpose), where we have combined arms offensive with players enough that we can have enrcirclements, breakthroughs, real counter-attacks, real delays and such. As great as our schwere panzer modelle Lars von Hamsenbumsen might be invincible in almost any basic tank battle and has enough firepower to destroy a single town in one shell is going to do when it is encircled, being targeted from two or more sides or is having unwanted guests in top of the hull?