I'll end this right now. I have never read the manga until the the gmg arc, while the anime was on break. Now that I have read the phantom arc there's me re than enough evidence to end this. In the Phantom arc, Natsu fought the guy totomaru, which was a bad matchup becuase he controls fire and was using it to make Natsu punch his own face. After Natsu destroyed the source of the cannon, Gray arrived and froze totomaru, Elfman threw him into the sky. After that Natsu got the shit beaten out of him by Aria, who was toying with Natsu. Erza came to save his ass when Aria got behind him and was about to do the same thing he did when he caught Makarov off guard. That's when Aria said he won't hold back against Erza and took off the blindfold that help his power back. Natsu was standing trying not to get blown away by the sheer power of Aria. Erza went thrusting in and one shot Aria.
Erza took a Jupiter shot before getting there, which put her in a much worse condition than the small stuff totomaru did to Natsu. You cannot use excuses that the guild master Jose said Gajeel was his strongest, which was a complement to Gajeel for capturing Lucy again. The proof was not from words. It was in the fights. After Natsu got saved by Erza, because he was outclassed by phantom's s class Aria, he was even with Gajeel proving that Aria was stronger than Gajeel, and that Erza was very far ahead of Natsu during that arc. Natsu wasn't taken seriously against Aria even while in holding back his power blindfolded. Erza took Aria out in one shot, while Aria gave his best. That ends this discussion that Natsu was not anywhere near the level of Erza that time.
In the gmg, if you watched the anime, you should have seen how Erza's pupils and iris in her eyes were constantly changing in size, showing great concern of how strong Bacchus got. She looked like she shit her pants. But all you can say is Erza said Natsu was as strong as her. Therefore Bacchus did not lag behind Erza. Gray also said he can see why Bacchus is on parr with Erza, and freaked even more when he knew Bacchus was not even trying. You want to talk about the Elfman fight? Bacchus taking it easy, extra easy because he didn't even drink, but he was literally giving one hit at a time which sent Elfman flying into the wall. And each hit sent Elfman flying. Elfman was face down on the ground until he got up and used his lizard armor. Both Bacchus armor and Elfman's armor crumbled as you could see Bacchus purple armor in pieces and Lizard armor scales flying around also. Meaning he broke Elfman's armor. Why do you think Elfman's transformation went away? It's because he got beaten up and couldn't take anymore, the same time Bacchus exhausted himself. Bacchus got up off his knees, said a few words acknowledging Elfman for taking the pain, then he fell laying down from exhaustion. Elfman couldn't even get off his knees. After the fight Elfman was in the infirmary with his whole body in bandages. Mira said that lizard armor is perfect against hand to hand combatants, and also said that Bacchus can break lizard armor, which he did.
So your talk about Natsu having been as strong as Erza since the phantom arc is gone. I've given you a few pieces of evidence that showed Bacchus was still a good match against Erza. All youve said was that her fights with Bacchus were long ago, which is what you wish were true, but have no evidence to back it up. I said he demonstrated great strength, speed and skills, that even now Erza had concern in her eyes showing she still sees he is still up there. That's more evidence to prove he's still a good match against her, than you making up stories claiming it was long ago, and you said Erza was low tier at that time, which she never was because she was always stronger than Natsu and Gray since they were kids. If you don't tap I keep going.
To make you feel better, in this Alvarez arc Natsu showed more than Erza. The past is different.