I think the portraits as far as posing, expressions, sharpness, etc. are excellent. Where you kind of lost me on the first one is the grayness; I'd go with a ligher touch in adjusting the tint/tone.
On the helmet in the first that lettering was most likely off white, but seems like if anything it maybe should be a bit warmer in tone while still being a bit grungy from wear. I don't get gritty, I just get too gray heading into drab. (I can't unsee that white part of the helmet and how gray that is.) The skin tone got too gray, and I'd expect the red and the yellow reflective(?) stripes on the jacket to stand out a bit more even if it's worn and the color is no longer vibrant.
I guess I'm thinking about grungy hockey, where pads have black knicks and scrapes etc. but the color isn't grayish, it's off white (with grime). Maybe borrow/use an older jacket just for some test shots and think about what does it look like? Are there marks from use? Figure out how you can show those to get a gritty feel and not go too artificial with it.