It can't be that hard to improve when you are absolute shit really.
It's like a 5"7 dude weighing 320 pounds. If he loses 20 pounds, it's an improvement. After all, things can't get much worse for him, or he risks dying, so the 20 pound loss is an improvement, albeit a slight one. However, were he to lose 120 pounds, than that would be a massive improvement. It's like Pepe transforming into Hazard or Robben. It's not going to ever happen, let alone happen overnight.