Re the large sleeves, check the tag and see if it's a goalie jersey, they make the sleeves shorter & wider for goalie jerseys...
Re the knockoff jerseys, always check inside the jersey to make sure the numbers are sewn right thru the jersey, there are a lot of heat sealed numbers that look like they are sewn on, and for the name plate, from the inside of the jersey press your fingers along the underside of the name plate, if you can't feel stitching, it's a fake...