Nordic Combined I fear is something of a moribund sport as an international competition. I don't think Frenzel, Rydzek or Rießle are that much better than champions of previous years, but that the competition has just wilted away through a variety of factors. Austria have never really replaced Felix Gottwald and now Bernhard Gruber is getting older, the likes of Orter just haven't got to the same level of recognition. The Japanese have never quite broken through mainly as Akito Watabe is like wintersport's answer to Emma Johansson, continually being good enough on near enough any course to make the top 10, savvy enough to make the right moves towards the podium but seldom strong enough to win, and the French have pulled back a lot of funding since the retirement of Jason Lamy Chappuis. A few of the strongest jumpers were simply not strong enough on the skis (in fact some of the more extreme examples include Evgeny Klimov, now the Russians' best ski jumper, who switched from Nordic Combined before last season after some disastrous ski outings), while the Germans' main rivals come from the Norwegians, for whom there's only really the young prospect Riiber (who is the most likely to upset the German results whitewash, but also is developing quite an injury problem for someone so young) and Klemetsen (who is not a fast skier and is getting old) who are consistent jumpers; they have several fast skiers like Graabak, Moan and Kokslien but they're seemingly always starting too far back.
The sport has tried to rejuvenate itself by introducing new formats in recent years, because Gundersen after Gundersen makes it pretty formulaic, and the hopp portion isn't always broadcast in some nations, leaving it just a handicap start skiing race with people who aren't as quick as the specialists or the biathletes. Things like the penalty race were scrapped as too confusing (and the differences between penalty sections too loose as somebody could jump nearly 10m further and gain nothing from it if they didn't cross a penalty line), and the Team Sprint needs to be, it lacks even the tiny element of interest that it does in XC when done with handicap start, but they show that the FIS is trying to invigorate interest in the sport, because one country winning everything does little for viewer interest, as we've found in XC especially among women's races in recent years. Especially when, with all due respect to him, Eric Frenzel is not as media-ready a personality as Lamy Chappuis was, or similarly dominant champions in other FIS disciplines. He's too shy, too quiet, a bit too bland a personality to really market hard for many people.
So how does somebody get into NoCo? It's got to be from ski jumpers, right? After all, if you're a budding ski jumper and you can't quite make the grade, you might be useful with a pair of skate skis on your feet, and then you keep on doing what you're doing. But for a budding XC skier, it's a lot harder to justify moving to NoCo, because if you feel you want to move away from pure XC, biathlon is much quicker to pick up, and in many respects much safer, because it's easier as an adult to learn shooting from scratch than to learn ski jumping from scratch when you're already physically built for XC skiing, because the kind of musculature required for ski jumping is so different from that needed for XC. I know that the Germans keep their young ski jump talents involved in XC until they're ready to take them to the pro competitions (there are pictures around online of established German ski jumpers like Freund and Wellinger rollerskiing or in the Loipe as youngsters), presumably with a view to converting some to NoCo if necessary or if they show a particular aptitude for it. I assume other teams must need to do similar because NoCo isn't a sport you just stumble onto and decide "I want to do that", not least because both of its constituent elements have a lot more money in them.
None of which has anything to do with doping or any bearing on how suspicious the domination of the sport by the German team at present is, of course, but just elaborating on the sport itself and why it's in the position it is.