I use the VPP angle (value per position.)
If there's a huge gap in WR/TE/QB/HB talent you take a guy early that's above his "true value" because it gives you a season long scoring advantage.
I took Gonzo in rounds 3 or 4 for years. HUGE boost to my team.
Considering your league I'd keep Gronk (for once he'll be an early bust and late payoff) and draft to complete your roster.
2HB's (I hate both your HB's. Spiller trips and misses time and Johnson is damaged goods. Johnson is great trade bait though. Wait for his first huge game and then float him out there.)
If this league is so WR heavy I'd guess it's also QB heavy in scoring. There are a ton of solid QB's this season. Spend your time on HB's/WR's that you can use for trade bait and worry about a QB later...
"He had no teeth, and he was slobbering all over himself. I'm thinking, 'You can have your money back, just get me out of here. Let me go be an accountant." I can't tell you how badly I wanted out of there."
Denver rookie QB John Elway, on Jack Lambert, after Lambert and the Steelers knocked Elway out of his first game as a pro (1983).