My obvious answer was NFL. But then realized the NFL is set up for bad teams to succeed. Look at the NFC east. The same team has not won it back to back in a long time. You hit on the right QB, either in FA or the draft and it can be a quick fix. My answer is baseball bc ONE main player could NEVER make as drastic of a change as in the NBA or NFL. One Great pitcher in baseball will never make the impact that ONE great QB can. Same thing on Offense. Your best hitter only gets 4 attempts to impact the game and your best starting pitcher is on the bench for 4 games after he plays. Also the players that get drafted spend 2-4 years developing playing minor league ball, so you really have to hit on the draft and hope the dudes develop right for the nect 2-4 years