You can see the baseball contest ad on the back panel. It's the front flap though, that is quite intriguing:
We've seen the insert card version of the contest before. The contest to my mind served two purposes:
1) Sell more Bazooka and Blony;
2) Find out where entrants live in an early data mining exercise.
I'm not sure if $5 a week for six months was a better deal than a 17 inch portable TV back in 1958!