I don't know that he's even been capable of being "the guy" in the LW division.
He leap frogged the entire division to get a title shot against an opponent who was really a favorable match up. Alvarez is a game fighter, but you could wobble him with a tickle.
He wasn't exactly knocking guys dead at 145, he TKO'd guys (Aldo is the only one he put to sleep.) Its much more likely that his power wouldn't have been the equalizer at this WC (it hasn't been so far, both Porier and Khabib have said as much) that it was in a lower one. I don't know that the rest of his skills would have been enough to make up for that. He has some nice kicks in his arsenal, but nothing overly special and as a grappler his defense is pretty solid, but he has no real offense to speak of in that regard.
The game has moved beyond him for sure though. He's got his hands in so many pots while the rest of his competition have been spending time in the gym. This is pretty reminiscent of the way things went for Ronda. Hes handled losing a zillion times better than she did, but shes another fighter who would have benefited massively from switching camps or at least doing a full camp at another gym (which is what Conor should do if he is to fight again.)
There's gotta be a Jeremy Stephens / "Who da fook is that guy?" joke in here somewhere
I definitely think Conor's left hand has been overly mythicized because of the Aldo KO, but he still has a lot of power. The only guys he's ever beat by decision were Max and Nate who both have legendary chins, and he dropped Nate.
I think the problem with Conor's power is 3 fold:
1. As you mentioned, it's not the touch of death at LW.
2. It doesn't carry later into the fight. I think we saw in both the Khabib and Nate fights and kind of even the Mayweather fight, that when he tires out a little bit, his punches don't have the same zip on them. He kind of starts throwing arm punches.
3. The most interesting fights left for him are guys with rock chins. Poirier, Nate, Gaethje, Tony, Max. LW is full of killers and you don't make it very far up the rankings without being able to take a punch.
I think Nate is the best fight for him. Nate will probably be able to eat his shots again and he'll have to dig down to find a way to win R3, R4, or R5 to win by decision. I think those others guys have a good chance of eating his shots too, but they are more dangerous and could stop Conor ala Poirier.