I guess the top WR gets $10M to 15M a Year (Diggs)
your 2nd and 3rd WRs get 7-10M a year (Brown, Beasley)
your 4th and 5th WRs get $750K to $3M a year...
If you split your cap approximately by 1/8th (one for each skill position), then you have about $25M of your Cap to spend on WRs... If you spent 20+ on the 1st three then the 4th and 5th are playing rookie contracts or minimum wages.