The question assumes he'll enter the draft in the same position he would next year as this year's, which is faulty.
Many would argue the chance to increase his draft position for the following year, which is likely if he returns to BYU, would pay long term dividends far in excess of the formula presented here. I among the many believe he proved he's the "go to" guy this year and will reap the rewards in terms of stats next year, which will (barring injury perhaps) shoot his draft stock up.
UDFA status clearly undervalues what we Cougar Fans have seen he can do. This guy is absolutely an NFL receiver; he just needs the chance to showcase it one more year to everyone else.