It's an expectations issue. I take Don to be responding to inflated expectations (corresponding to one side of the pre-signing debate), and saying that, as a goal-scorer, so far, he's in fact not "elite."
Don Pacifico you don't buy the top goalscorer in Europe if you weren't expecting him to significantly contribute on the goals front. If that's not a relevant criteria then we could have bought plenty other options out there, for a fair bit less money.
IMO this is the wrong yardstick. For me the whole point is exactly what we've gotten so far - he scores enough goals, and is an all-around good enough striker, to allow us to survive a major injury to Havertz. I also think that this more modest level of expectations corresponds to what we paid (similarly for Madueke).
But I also think he's an awkward fit with our play style, which limits how much he's likely to score for us (whereas he might score considerably more for a counter-attacking PL team like Forest under Nuno). I think part of the high expectations thing was a hope among part of the fanbase (and some posters here) that his presence would force Arteta to change our play style. People wanted a savior from haramball. Our style is changing but that has more to do with Calafiori and Zubimendi than with Gyökeres.
We're top of the table, he's doing what we need.