Uh yeahnif you had actually seen barrera jones 2, oscar mosley 2 and mosley forrest 2 ypu would have seen that they DID infact do better in their rematches even if they didnt get the Win
You can say most of the times but not always . Forrest vs. Mayorga 2 and Hearns vs. Barkley 2 come to mind.
I'm going to give you the benefit of the doubt here in believing/hoping this usage of "why come" is just a parody of @El Chicano and this periphrastic garbage isn't actually just some quirk of your lexicon that I've spent five years somehow failing to notice. On principle, the moment somebody utters "why come" unironically I have to cease taking anything said by them seriously.
To answer the OP: I believe Canelo did better in the rematch than in 2017. I also believe that GGG happens to be the superior boxer. (not just fighter, boxer. I don't buy the "Canelo is a slick technician" narrative that has cropped up in the last couple of years. I remember him as the guy whiffing badly for 12 rounds against Mayweather and Lara, with nothing the kid has done in the ring since fully erasing that view. People act like he underwent some 180 turn, and...no. He didn't. He always was a boxer-puncher with a slightly above-average skill-set and exceptional athleticism...nothing has changed since he was a teenager, in that respect) So...there ya go.
Authentic greats always overturn controversial results with a win in the rematch. The better fighter will improve their performance by making the necessary adjustments and that was Canelo. This trend is reflected throughout history.
I agree, Golovkin boxed better. Canelo managed to plug his gas tank and was busier - and therefore more competitive - this time round. But he lost.
The "always" notion has been taken down so many times in this thread, and with so many big to huge names, that we can already call it a fail.
Froch clearly done better in the Groves rematch when he sparked him out for the count. Oscar deserved to beat Mosely second time around.