Not only with Blue. It's the same with SSG or even SSJ3. The problem isn't Blue. The problem is terrible world building. I'm not against the idea of 17 becoming really strong. Actually, I expected this to happen since it'd have made sense at least. The problem is how everything is brought:
Dude trained on a island fighting nothing but dumb hunters with guns. Stuff that freakin Radditz could've handled. He got good enough to stand a chance against a "god transformation". Which happened through an extensive harsh training with Whis, which is supposedly the body guard of a divinity, a training that is meant for special beings.
It's basically a "fuck logic, fuck power level" done terribly wrong. It's basically TFS "Push-ups, sit-ups and PLENTYYY of juice".
They are trying to make irrelevant characters relevant again in a terrible way. Krillin for exemple stopped training for years. He took on training back with basically musculation materiels, weights and such. Goku kept training for 30 years, going through regular Roshi training, then Karin's training, then Kami, then Kaio, then *100 gravity, then Yardat, then Other World, then Whis. He's supposed to be not only really skilled but also be really experienced. Yet we're getting boring fights with silly mistakes, all for that to make up for the fact that Krillin was irrelevant and the only way they did to make him relevant was basic training MusculationGAF is doing already and making a skilled experienced fighter an idiot.
Either make some intelligent world building or create new characters if you can't be good enough for the former.