The only thing that was a bit thick was my prose.  The old criticism is that if the pedigree were true, then two children of AEthelred II would be marrying two descendants of AEthelric, the first one generation down, the second 4 generations down.  Hart basically rejected this as absurd on its face, that you could have such a 3 generation difference - Edward marrying his brother-in-law's great-grandniece. Kelley argues that Edward was a generation younger than his half-sister, so the three generation difference becomes two.  Eadric at 40 could have married a 18-year old daughter of AEthelred, meaning the generation difference is now only 1.  Edward could have married an Eadgyth a half-generation or more younger than he was, and Eadric could have been a half-generation younger than his brother AEthelmaer, completely removing the chronological problem.  He was basically saying that, as ridiculous as the difference in generations appears on first glance, it is not as unlikely as it might seem. 
 As to why he is explaining away the AEthelric pedigree, one of the earlier authors had accepted the descend from Wulfric to AEthelmaer, and then suggested that Florence (recte John) had been confused between two AEthelmaers, and that Eadric was not brother of AEthelmaer the Stout.  Kelley is simply saying that this need not be the case, that Eadric could have been brother of AEthelmaer the Stout, that the siblings shown by John of W could all be the children of AEthelweard.  He suggests three possible explanations: A) that one pedigree showing Godwin son of Wulfnoth son of AEthelmaer was mistakenly or fraudulently linked into a second that showed Eadric Streona as son of AEthelric, B) there was an mistaken exchanging two names, such that the authentic pedigree originally showed Eadric, AEthelmaer and an AEthelric as sons of AEthelweard, and somewhere along the lines this was transposed as Eadric, AEthelmaer and AEthelweard as children of AEthelric, or C) that the authentic original pedigree showed the same brothers as sons of AEthel-weard, son of Ead-ric, and a mistaken contraction of these two generations resulted in them simply becoming AEthel-ric. Kelley favors explanation B.