CONTEST -What do the following cards have in common?

Take a look at the 5 cards below and tell me what they have in common. They have more than one thing in common, but I am looking for something specific. Email me the answer I am looking for (daniel24303 at gmail.com) and I will select a winner at random. To win you must follow my blog and I must receive your answer by 11:59 pm on Tuesday September 8th. The winner will receive a card, or cards, to be named later. I will make it worth your while. If you win, tell me who you collect (team and player) and I will put together a nice prize package for you.

Good luck everyone!