Very nice! The only negative is the watermark on the back. Think it should look much better without it. :-)

Very Nice! make this with the other badge?! Include the watermark?!

Brilliant...

Is very nice simple design, very good use simple but beautiful lines, my suggestion would be change the logo of PZPN and put the more polish eagle and at the bottom of the t-shirt in the right side put a little logo that say Polska with the wing and the ball. A little add in the neck in the back side like Polski or Polska or Tylko Polski(only polish) something like that.
The number font change it and the number put it a little more down i think is to up.

I cant recognize it as polish, add Polska logo in some place, only because i know what does it means PZPN i know is t-shirt of Poland, else i wouldnt know.