Madden's player abilities are a controversial topic, but they don't seem to be leaving the game anytime soon. Making them work for you is well worth it to win games. Let's get you setup to win games with the most important player on the field: the quarterback.
The Sideline Deadeye ability grants your signal caller perfect passes on all throws outside the numbers, except high and low throws. The Inside Deadeye ability grants perfect passes on all throws inside the numbers. You probably see where I'm going with this. Combining the two abilities means your QB will throw nothing but perfect passes, represented in game by blue passing meters above the wide receiver's head.
Now it's important to remember that a perfect throw doesn't always mean a perfect play. All the abilities of defenders near your receiver will still get checked. Those guys get paid too. They can still light a receiver up after the catch, forcing a fumble. And sometimes, as in real life, wide receivers drop balls that are placed right in their hands. Looking at you, Marvin Harrison Jr.
But it's easier to win a game in which you throw 22 or 23 perfect passes out of 30. These abilities also make it easier to activate X-Factors, as they often require you to complete a certain number of passes to unlock their benefits.
Those QB X-Factors can then help activate wide receiver abilties, and before you know it you have a QB-WR combo looking vintage Joe Montana and Jerry Rice out there.