I've read a few articles, Steeple, Bild and another which I can't remember
They've all had a slightly different slant, Steeple not mentioning the 200/400 but the Bild one did, although it wasn't clear to me whether that was indoors or just the odd one occasionally (including outdoors) as my German is rusty!
All seemed to be saying that she can't do the weight training necessary for the HJ and as she has good speed the LJ makes sense, but only if she can go over 6.50 or there's no point.
I remember seeing Friedrich jump at the European Cup in 2005 and thinking she approaches the bar so fast, she should do the LJ. I think Chaunte Lowe's 2.05/6.90 may have inspired her