WR separation

[RUSK97]

It's hard to recall our WRs (not named Carroo) getting consistent separation the last two years. It's easy to blame the QB, but it seems whenever Nova/Lav dropped back, the WRs were blanketed. I know it's a combination of factors, but what's the biggest reason: 1) players' lack of speed 2) predictable routes 3) players not running the right routes 4) better opposing DBs 5) ???