Tom Brady wants to see Cowboys quarterback Dak Prescott prove he is worth the historic contract he signed Sunday. To do that, he believes the Prescott has to find success in the playoffs. The quarterback has spent his entire nine-year career in Dallas but has just a 2-5 postseason record during that time. He is coming off of his most successful statistical season with 4,516 yards passing and a career-high 36 touchdowns to nine interceptions. CLICK HERE to go to PrizePicks and use code ON3 to receive a guaranteed $50 once you play $5 in lineups! That earned him the four-year extension worth $24…