Not here to critique him per se because Mata and Robin have equally underwhelming if not more so. But even leaving the natural physical decline aside - there's something I've noticed a lot in recent years and probably lots of supporters have done the same : Wayne just doesn't seem to have the bullishness of the younger version which made believers of all of us.
When he arrived at United and even during the mid to late-ish 2000s, he just seemed to be a bit of an X-rated nutter on the field who gave no effs, always crunching into tackles, harrying and hounding the nearest ball carrier, messing with opposition players, sarcastically applauding referee decisions. That ability is still evident in flashes particularly under DM last season but not for sustained periods.
I do wonder if in trying to contain that renegade behavior Fergie instead neutered one aspect that made him such a dangerous player. Maybe he should've been left alone and didn't need tampering. You no longer see that fierce competitive glint and fierce desire in his eyes that was so trademark Rooney and that is a bit of a travesty. He was the ultimate blue-collar player back then. Just seems too PR friendly now for lack of a better word. Please turn the beast mode back on Wayne.