Well, that's kind of the thing, right? If you get the deal done, you have Beckham coming off the books at about the same time you have Murray lined up for an extension. There's no point in pinching pennies when you have a QB on a rookie contract.
Even great WRs take a little time to get up to speed — and their careers don't always match up with their draft status. A.J. Brown looks like a manimal right now, and he was selected 51st overall. Marquise Brown is having a nice season, and he has work to do to get to 800 yards.
At the WR position, I think you pay the price to get the sure thing. I'd rather spend my top 10 draft pick on a guy who will affect every play on his side of the ball.