Interesting. I have to admit I didn't expect so high germanic influence in East Prussia.
I'm baffled by Old Prussians numbers too. For example we have figures for I1 around 6% in Poland and Russia, but importantly also 6% for Lithuania and Latvia. These are the lowest numbers for adjacent areas, because we have bigger numbers in Estonia, Finland and Germany for I1. It is hard for me too believe that somehow Old Prussia was immune against I1 haplogroup.
These are their closest Baltic cousins.
Lithuania (form Eupedia) R1a 38%, R1b 5%, N 42%, I1 6%, Latvia R1a 40, R1b 12%, N 38%, I1 6%
If Old Prussians were their true blood brothers and not only cultural, it should average for them:
R1a 41%, R1b 10%, N 42%, I1 7% (at 100%)
Now it is hard to say if Templars were mostly North or South Germans, or how many of them where mercenaries from other parts of Western Europe. I'm not sure how many Germans moved as trades/immigrants into Prussian's cities later. I know there were many in Poland at this time, I assume there were many in German speaking Prussia.
Old Prussians were the most east Balts, bordering with east Germanics for perhaps a thousand years. I would expect their N to be lower then Lithuanian's and I1 higher, and in disagreement with Old Prussian numbers from post above.
Seeing many unknown I would concentrate on N haplogroup the most, as it was almost nonexistent in Teutonic Knights and in German Immigrants. And if we can trust N percentile in Baltic area, and study of East Prussians.
When I do this formula =(N 40%-28%)*100/ N 40% = 30% shift in N.
The rest of numbers might be too speculative for good conclusions.
I'm still surprised. I didn't expect this shift to go over 20%, perhaps even as low as 10%.