There was really a shift lately. I feel like Gyro is taking Caesar's role more than Baron Zepelli in that he's not just a mentor who Johnny relied on anymore. It shows how much Johnny's grown, and how they are both equals in this race rather than teacher and disciple as it felt like before.
I really like this chapter too because it questions Gyro's ambition to save this boy who he barely knows. I think he's just as determined as the rest of the nut cases of the race, and really, choosing to fight for Marco is like one of the first big things he did for himself in his life, but it's also not the same 'hunger' as the others. It's more like it's the first time that hes really rebelled in his life, while the others are fighting for selfish means to further themselves. Like Gyro is literally fighting for a guy who probably won't ever know why he is (which does kind of show his noble nature though)
Not to say that a selfish desire is bad, cause look at Johnny's desire in contrast to Dio's. Dio wants to get more and to stand above everyone, while Johnny just wants to get back to 'zero'; like where he used to be. After the incident, his life literally fell apart, and I'm not sure abt his 2 years between the incident and the race, but I'm awfully sure that he was suddenly thrust into a impoverished state. I think his desire to get his legs back is basically the accumulation of everything hes wanted for so long- but mostly a purpose (as I think he said somewhere in the beginning of the story.)