Defensive fighting was not Stalin’s thing. At all. The Soviets were pressed hard by desperation, lack of time, and self-inflicted institutional brain drain. They never had the time or the resources to plan a deliberate defense-in-depth.
Kursk was the first time they could really take a knee, think through their strategy, and bring in the appropriate resources. Stalin had to trust his generals, exercise patience, and endure setbacks while the Germans wore themselves out. And he had restrain his impulse to execute someone every time things didn’t go his way.
One of the reasons Kursk was so significant was that the Soviets were able and willing to adopt strategies they had never been able to use before.
250 is definitely much too low considering a broad definition in time and space of ‘Battle of Kursk’, even just considering total losses, but including tanks which were repairable but not recoverable. Thomas Jentz’ books were mainly transcriptions of German unit reports and other records rather than a cohesive narrative of tank development or use. But at the same time they let the reader get close to the sources. In “Panzertruppen” Vol 2 he doesn’t give comparable figures for the whole battle (which is sometimes defined as extending into late August) but quotes Army Group Center’s tank losses just in July as 304 total write offs of 746 operational June 30. Army Group South suffered 259 total write offs of 1035 tanks, also in July. An important component of the Army Group South tank force was the Panthers of Pz. Rgt. 39, the first combat deployment of that type, around 200 to start with. 84 were total losses in July, but 156 total losses by Aug 11, including some replacements. Total losses escalated sharply as the Germans actually began to lose ground and couldn’t recover repairable tanks.
The graph Jentz gives for total German tank strength on the Eastern Front over 1943 showed 2,584 available of which 2,287 operational June 30, 2,020 of which 926 operational Aug 20, including an unspecified number of replacements so it’s coincidental that the available number dropped by almost the same as total losses of the two Army Groups just in July.
That said, the German total losses were certainly not of the order of 2,000, that’s the ballpark of their total tank strength, and most tanks which became non-operational by Aug 20 were still in German hands and repairable, nor were replacements a huge number in that relatively short period. Many of the non-operational tanks, of course, had suffered mechanical breakdowns rather than being knocked out by Soviet AT weapons.