Did the Supreme Court err in part III of Teva v. Sandoz?

As to the Supreme Court decision in Teva v. Sandoz, conventional wisdom before the case suggested Rule 52 would apply as to findings of fact by district courts in patent cases.  Of the outcome, the ABA Journal noted

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Breyer said the appeals court has to defer to the federal district court absent “clear error.” The Federal Rules of Civil Procedure establish the “clearly erroneous” standard for review of a district judge’s findings of fact, and there is no reason to create an exception for factual underpinnings in patent cases, Breyer said.
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That understood, the issue not so clearly resolved by the 7-2 vote was "what are" findings of fact?  The two dissenters, and IPBiz, do not believe that crediting the opinion of an expert is a finding of fact.  Seven votes said  crediting an opinion is a factual finding.  That is where the Teva outcome becomes interesting.  In Teva, accepting that one of ordinary skill understood that molecular weight from a GPC curve "was" the peak in the size exclusion curve was outcome determinative of the legal issue.  But this view is an opinion, not a fact.  From a GPC curve, one can determine a number average molecular weight, which in most instances is not the value of the "peak" molecular weight.

IPBiz had noted on July 27, 2013:

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The CAFC stated the peak average molecular weight Mp is the 
molecular weight of the most abundant molecule in the sample, so that it is not an "average" molecular weight." The CAFC also noted that Mn is the total mass of all molecules divided by the number of molecules, but did not give a definition for Mw. For completeness, Mw is the sum of the (square of molecular weight X number with that molecular weight) divided by sum of (molecular weight X number with that molecular weight).) 
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This text becomes interesting in view of part III of the Supreme Court decision in Teva,
which states in part:

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 We can illustrate our holding by considering an instancein which Teva, with the support of the Solicitor General, argues that the Federal Circuit wrongly reviewed the District Court’s factual finding de novo. See Brief for Petitioners 54–56; Brief for United States as Amicus Curiae 31–32. Recall that Teva’s patent claim specifies anactive ingredient with a “molecular weight of about 5 to 9kilodaltons.” Recall Sandoz’s basic argument, namely thatthe term “molecular weight” is indefinite or ambiguous.The term might refer to the weight of the most numerousmolecule, it might refer to weight as calculated by the average weight of all molecules, or it might refer to weight as calculated by an average in which heavier moleculescount for more. The claim, Sandoz argues, does not tell uswhich way we should calculate weight. See Part I, supra.To illustrate, imagine we have a sample of copolymer-1 (the active ingredient) made up of 10 molecules: 4 weigh 6 kilodaltons each, 3 weigh 8 kilodaltons each, and 3 weigh9 kilodaltons each. Using the first method of calculation,the “molecular weight” would be 6 kilodaltons, the weight of the most prevalent molecule. Using the second method,the molecular weight would be 7.5 (total weight, 75, di- vided by the number of molecules, 10). Using the thirdmethod, the molecular weight would be more than 8, depend-
ing upon how much extra weight we gave to the heavier molecules.
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Although the Supreme Court did not define the "third method," IPBiz had given the definition of
"weight average" molecular weight (Mw) in July 2013.  Applying the formula, one has
(4x36 + 3x64 + 3x81)/(4x6 + 3x8 + 3x9) = 579/75= 7.72, which is less than 8, in contrast to the "more than 8" in the Supreme Court opinion.  Although one does not know the Supreme Court's
third method, one of ordinary skill would likely calculate Mw, once Mp and Mn were known.
The entire uncertainty in this goes to illustrate the specific uncertainty when one fails to explicitly define what one means by "molecular weight.  One of ordinary skill does not know the bounds of the claim.


--Separately, the Supreme Court got into an inconsistency argument, which is of less significance
than the lack of definition of molecular weight in the first place:

Teva argued in the District Court that the term “molecular weight” in the patent meant molecular weight calculated in the first way (the weight of the most prevalentmolecule, or peak average molecular weight). Sandoz, however, argued that figure 1 of the patent showed that Teva could not be right. 810 F. Supp. 2d, at 590. (Wehave set forth figure 1 in the Appendix, infra). That figure, said Sandoz, helped to show that the patent term did not refer to the first method of calculation. Figure 1 showshow the weights of a sample’s molecules were distributedin three different samples. The curves indicate the number of molecules of each weight that were present in each of the three. For example, the figure’s legend says that the first sample’s “molecular weight” is 7.7. According toTeva, that should mean that molecules weighing 7.7 kilodaltons were the most prevalent molecules in the sample.But, look at the curve, said Sandoz. It shows that the most prevalent molecule weighed, not 7.7 kilodaltons, but slightly less than 7.7 (about 6.8) kilodaltons. See App.138a–139a. After all, the peak of the first molecular weight distribution curve (the solid curve in the figure) is
not at precisely 7.7 kilodaltons, but at a point just before
7.7. Thus, argued Sandoz, the figure shows that the patent claim term “molecular weight” did not mean molecular weight calculated by the first method. It must mean something else. It is indefinite. 810 F. Supp. 2d, at 590.
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