In response to your post,
@Kantos
I agree with you for the most part, except DeS Gray dominating Invel pre ice lock, which is clearly the opposite. While it is true DeS Gray took Invel by surprise, you can't claim that DeS Gray is superior to Invel, or that he was dominating, or that he was even a threat to him, because that was just one attack that Invel received. After that attack, Invel rose the guard and then anything Gray did was futile.
In any case, it's not that I don't like the way in which spriggans are being dealt with: I don't, but that's not the point. The point is, don't hype up a set of 12 characters and make it tacit that they're individually superior to each and every mage in Ishgar, to then have them easily fodderized by some unjustified and borderline stupid power growth in the MC.
When I mention PiS I mean PoF, since for me it's the same in 80% of the cases. In FT the way that PoF is used to justify the unjustifiable is plain ridiculous if compared to other shounen which are more realistic (within the realm of fantasy) => Naruto is an example. Even if some claim it is PiS that he received a powerup from the sage of the six paths, it makes sense since it was the only way to defeat Madara. It would be as if Natsu and Gray could not defeat August/Zeref/Irene/whoever, and they received a certain powerup by a certain someone. For example, Fairy Heart. It would make sense.
Now I don't know if you're knowledgeable of Naruto, but imagine Naruto is using Kurama mode (No SPSM mode, he didn't receive it) and he is fighting Madara (Juudara, the Madara which absorbed the Sinjuu). It's clear the gap between them is of at least a couple of solid tiers. There is no way Naruto can win. Now, Naruto is in base since his mode has run out, he's kind of powerless... and Madara kills Sakura. Naruto gets superbloodlusted and magically he is, in base, around 4-5 tiers stronger than he was and he can fight Madara equally, or even be above himself. That would make no sense at all.
Well I feel the same way. Not even DeS Gray was a threat to Invel, but then base Gray is all bloodlusted and is more powerful than Invel.
My opinion on the topic: Mashima initially wanted the spriggans to be massively more powerful than the Ishgar side, individually; to the extent not even the MC could solo one. It is not my opinion, it's what he tried to do by hyping them so much and showing some portrayal. But then, for whatever reason(s), he decided that he had to change that to the opposite and do so as gradually as possible in order to make sense- but sadly, he didn't achieve it. Let me give you a few examples:
If you take a close look to how the events and encounters with the spriggans were, Mashima became more and more lenient every time: First of all, Mashima had the main cast initially fodderized by a spriggan LACKEY (Marin), Brandish didn't even need to intervene, she just showed them the magnitude of their power. They were like scaredy cats then. I'm taking into account here the fact that Gray didn't even use his DeS mode, or that Natsu wasn't even trying; but heck, there 'was' a reason to try, since Lucy and Erza had just disappeared. I think it was a reason for Natsu and Gray to be serious, so I'm gonna assume they kind of were (even if they were in base). (Mashima's intention: Spriggans >>>>>> anyone else)
Later, Mashima had them barely being capable of running away from Ajeel (Ajeel being boosted by Makarov, so unfazed by the multiple attacks of the MC, etc). Gray even went DeS and had one of his best spells used, and Ajeel was like "meh not bad, but not good enough by a mile", doesn't that give you the feeling that Ajeel is so superior to Gray (when it happens that it's the other way round, when Gray is bloodlusted at least?). Then, Laxus throwing a nuke that could've potentially hurt (even killed, as argued by some) Ajeel kind of changed the perspective of the spriggans being so massively powerful by a little bit. (Mashima's intention: Spriggans >>> anyone else, but certain characters may be a threat to them)
After that, Ajeel fought Erza (and Bisca) and it took the two of them to EXTREME diff a spriggan. Erza mustn't be so far from Natsu or Gray IMO. Later on, we have fights like Dimaria vs Chelia, which require a big sacrifice, "luck" (Ultear being there) and a lot of teamwork to defeat; Bradman, which requires reamwork + Gajeel to sacrifice himself to defeat him; Irene's lackeys, who can pose a threat to someone like Mirajane; August, who can probably casually obliterate anyone; Jacob, whose defeat required teamwork, outsmarting Jacob, Happy intervening (luck/chance) and Natsu using his strongest blow. Glidartz, namely the strongest person on Ishgar's side, received damage (scratches) from HALF a spriggan (God Serena)... Laxus (maybe the second strongest on Ishgar's side?) extreme diffed another one, but it was kind of like symbolic teamwork with his great grandparent. (Mashima's intention: If you combine your strength with an akin's one and give it your all, if your will is strong, you can defeat a spriggan)
And now, a few hours after that, we have Natsu casually one/two shotting a spriggan and bloodlusted Gray going up 2 or 3 tiers for the sake of it and defeating another one easily. (Mashima's intention: I initially wanted for the spriggan not to be defeated like this but for the setup I'm thinking it is necessary that the MC suddenly gets massively powered up just because). <- This is what I call PiS.
Now for the Gajeel argument, Gajeel received a powerup but it was "visible". It was Dragon Force. That is not exactly what I call PiS or PoF; he actually awakened a latent power that he had, and that we all know that boosts your base power by a lot; and that he had never used (and it was about time); so that was fine by me. You see, if DeS Gray (maybe fully demonized) could've beaten Invel with the same ease as his BASE MODE did, then it'd have been fine by me. I mean, if he had been bloodlusted but, besides, he had had his DeS mode active, then I wouldn't think of it as necessarily PiS.
As
@atomic_2000 very well pointed out, he (or I for that matter) aren't denying that Natsu/Gray are not spriggan tier AT ALL. I'm the first to defend that they are, but that does not mean that I don't also defend that it was asspull. "Tell me who from FT guild is a spriggan level character?" you ask me. Well it's hard to say. The ones who clearly are: Glidartz, Laxus, Jellal, Natsu and bloodlusted Gray. It is likely that bloodlusted Erza, Mirajane, and some others are as well. I mean I wouldn't be surprised. If bloodlust raises your power by 2 solid tiers, I can see Makarov or even Lucy taking out a spriggan... Now, the spriggans were "Unbeatable" precissely because of their hax. This is what I like about the ones who have hax: that you can be as powerful as you want, but tell me how Glidartz is negating timestop or magnification of vital organs... He probably can't.
You say "the Gray who was fighting in the beginning wasn't going all out". But that is a lame excuse- for me. Because I could understand that the difference between going all out (bloodlust) and not going all out (morals off) would be of one tier, one solid tier even; but the gap was just too unjustifiably big. Maybe it's only me who thinks that way, which is OK then, I might be wrong I'm not trying to persuade anyone of anything, it's just my perception of the facts. So does someone have to die now for a character to go all out or to be bloodlusted? Look at Tenrou Juvia, she got bloodlusted just by acnkowledging the possibility that Gray may be in trouble, and she went up one solid tier. That made sense for me. But having a character die in order to justify a boost in power of around 2-3 tiers, and the bloodlusted character not even using his strongest mode, appears ridiculous to me.
"We can also use portrayal to scale a character, so Base Gray would still be below Erza, but overall Gray should be above Erza." Right, I completely agree. But a hypothetical bloodlusted Erza would then automatically be above Gray, if she were to be boosted just as much as Gray was.
An appeal to popularity fallacy, just because 99% agrees doesn't mean it's right bud.
The possibility of something being right/wrong when 99% agree on it is 99% higher. So, yeah, if 99% agree on something, I may perceive it differently, but then it's 99% probable that I'm wrong, then I'm gonna have to recheck and then I'll probably see I was wrong and I'm gonna have to concede.