Lucas had his knee, but Henderson hasn't had a litany of injuries? Generally when he builds up a head of steam
Henderson isn't a defensive mid. Lucas had the grace of 5 years before he hit his stride in that position, in spite of working with some our greatest midfielders in recent memory. Henderson had a waning Gerrard and that's it.
So, Henderson has been dm for 2 seasons, both of which were curtailed by injury. Whereas lucas had 5 uninterrupted, then got injured, and never got back to that 6 month level.
We don't compare Henderson to other midfielders because there's little point. They are better. And what? Could compare every one of our players to someone else and they'd be last. De bruyne pisses over Coutinho from a great height, as does silva. And that's just man city. Mane and salah are arguably the only ones you could say could be the best in the league (but again thats subjective).