I am going off memory here, but you can adjust the color spectrum and desaturate all of the colors you dont want visible to grey. It is an old photographer’s trick…like when they take out all colors but red and leave a red rose. Any how, you can do the same thing with color balance or use the leaveColor effect, both under the Color Correction folder under the effects panel. Just apply the effect and desaturate all of the colors except the jersey colors of the team you want to retain. If you want to desaturate the rest of the surroundings, you can duplicate the footage, and animate a rough mask around your subject and desaturate the entire background. Obviously, this works best when you have distinct colors. The other way is to hand rotoscope out the footage you want to retain and desaturate the rest…this is a very time intensive option.
As for the player cut out coming forward, the quickest and most straight forward way I can think of is to stop motion the footage at the appropriate time, duplicate your layer. and then use a mask to cut out the player. Then just animate the scale of the masked player to make him grow over time, or if you want to, you can make the layers 3d and move the masked player footage forward towards the camera.
If you need more help, let me know