Austin, Keys and Lenzy were banged up pretty badly, and none of them saw significant playing time. Those guys were counted on to stretch the field vertically, and without the three best receivers being available, we had no choice but to turn to the next tier of players.
That being said, Javon McKinley turned in a reasonably good performance as WR1, and Ben Skowronek did come through in the clutch as a WR2, but neither were the type who could get enough separation from opposing defensive backs. Avery Davis did a good job as WR3, and was about as fast of a receiver as we had available, but he's not exactly a speed receiver.
Opposing defenses didn't have to respect the long ball, and instead simply squatted on the short and medium routes. At least it wasn't as bad as 2013, where Tommy Rees' only reliable throws were the short passing game. Opposing defenses didn't even have to respect the medium range passing game...