>>717575712
Power is mainly acceleration and how well they push out of traffic, though I'm not sure about the latter. I think it also affects their uphill speed. Pretty important for Umas that hand near the back and need to get past the pack, though they can still get boxed either from low wit or just plain shit luck
Guts (right now) reduces how much stamina your trainee drains in that last stretch. Training it isn't so important since the upper threshold for 'good enough' is about 300, and you can reach that easily just by training stamina. Any more and it's a waste, but conversely if you have no guts your trainee will just burn through all their stamina.
>>717575963
Power can be useful for Pace Chaser, since it gets pretty packed in the middle two positions.