It's not black or white. I don't think Gattuso is a mediocre coach. He's done a decent job for us results-wise, and his decisions make sense more often than not. I've been saying it since last season. It also clear the team has improved, the stronge spine, and above all the confidence. And players seem to love him.
But it's also 99% about Piatek. He's won us points from not even half chances but 1/3 chances, and has not missed a single important one. And usually scoring the crucial first goal or game deciders. He really makes the absolute best of a team that has a very hrd time creating chances.
And I also think there's a chance Rino is not the guy that can take us to the next level. I'm also a big proponent of the idea of only sacking him if there is someone clearly better though, and not only if we finish 4th. The guy is a solid coach. I don't see the sense in bringing another manager who will at best be the same. But if there is a chance to get a proven manager for once, we probably should aggressively go for it. I doesn't have to be only Guardiola/Conte/Sarri either. If we finish fourth and you told me we can sign Gasperini (just for an example), I don't think it would be a bad idea at all.
"It is possible to imagine a distant future in which most other species of life are extinct but the ocean will consist overwhelmingly of immortal jellyfish, a great gelatin consciousness everlasting".