Fourcade seems to struggle from not having the breaks for shooting bouts. Kaisa Mäkäräinen has said similar, she's had some very good results in races of up to 10k but says that's her threshold, above that recovery becomes an issue. So for those that aren't so dependent on the breaks that the shooting bouts gives them, the biathletes can have some pretty convincing results.
For example, in the Val di Fiemme Worlds in 2013, Miriam Gössner was half a second off a bronze medal in the 10k free, Mäkäräinen and Gasparin also managed results in the top 25 or so. Miri was a full minute faster than Denise Herrmann who is now one of the quicker female biathletes, but not the outright fastest save for at Östersund where she was way up there, and therefore serves as a good comparison point too. She is the 5th fastest women's biathlon this season according to the course time analysts at the Ukrainian fed; Domracheva, Kuzmina, Mäkäräinen and Aymonier - who is also a good comparison point to use, though transferred much younger so doesn't have the same body of work to compare as an XC skier as Denise - are the four who are faster. Lars Berger not only has that anomalous gold in the 15k at Sapporo (he was lucky with conditions, mind) but was also 4th in the World Championships two years earlier in Oberstdorf and, as well as OEB, he and Svendsen have done many relays for the Norwegian team, including in Lars' case a gold medal at the World Championships in the format (Gössner also has silver medals from the 2009 Worlds in Liberec where she set fastest leg time as a 19yo biathlete, and the 2010 Olympics when she admittedly spent the whole season on the XC team).
In the 50k at Sochi, due to fatigue, illnesses and injuries, a few XC teams were down on numbers and biathletes stepped in. This race isn't really representative as it's two and a half times longer than any biathlon race you'd normally see, but in that Arnd Peiffer was 40th and Erik Lesser 42nd, Milanko Petrović was 50th. The two Germans rank 14th and 15th for the season this year in terms of biathletes' speed.
I'd say that the likes of JTB and Fourcade could be relatively competitive over a relay leg at least, I reckon JTB can be more competitive than Fourcade over a 15k free as from his goes at Ruka and Sjusjøen we've seen Martin can be pretty competitive at the halfway stage then he falls away the longer the race goes on. They have a fairly sizable gap ahead of the rest of the field ski-speed-wise, then Benedikt Doll and Simon Schempp are next, although with Germany fairly peripheral in men's XC with their golden generation retiring, they probably wouldn't be too much of a downgrade.