There's more that goes into a 122.4 rating than just getting favorable match ups. A rating that high in the three biggest games of the year means that you're making the right decision and executing perfectly almost every time. In the Philly game, he had to recognize when Witten was going to be bracketed, and when Dez was going to be doubled. Against the Lions, he had to know where the run blitz was coming from and attack that empty spot. And you have to be extremely accurate, and you have to avoid mistakes completely. All while under the pressure of it being the most important game of the year at that point.
If Dak takes advantage of the match ups and ends up with a rating in the 100 range in the first three games, I guess you won't be impressed at all, because Elliott took all the pressure off him by helping to give him favorable match ups. Me, I'll be doing cartwheels, because a 100 rating would mean that he made the right decision more often than not, that he was executing, and that he handled blitzes while he was taking advantage of those match ups.