Actually, this study shows exactly the opposite of what the author is trying to claim. You test for difference of means precisely because the eyeball test isn't always conclusive.
And yes, it is appropriate to say that more sophisticated analysis is needed (e.g. controlling for opponent record, playoff game, etc). But I guess you can stick Harvard on your blog, and forgo methodological rigorousness altogether.
Why would he need to show results for playoff games or take into account opponent record when the study is purely about Rondo in games that are nationally televised or not nationally televised?
In what way is he skimping on the data when he never mentions how rondo plays in playoff games vs not? This was never mentioned in his introduction.
Its all very well to sit back in the armchair and say "this is a bare bones study because it lacks data for this, this, and this" when the writer has never even mentioned those things as variables in the brief before the data is actually presented.
It is a simple analysis of rondo in nationally televised games vs not nationally televised games. Use it for that purpose. I don't think the writer implies that you should use it for anything outside that purpose either.