Goodbye to small school prospects: Why fewer NFL players come from outside the FBS

North Dakota State tackle Grey Zabel is one of seven FCS players invited to the NFL combine this year .

Zabel said he had a few offers from bigger programs to enter the transfer portal.

"It's not just me. There's other very talented players that are getting tampered with every single year ," he says.

Cam Ward and Shedeur Sanders are two of the biggest names in this draft class.

A director of player personnel for a Group of 5 college football team laughed when told the number of total transfers for 2018 -- 18 ?! Seven players from his program transferred up this offseason and four transferred in from lower levels of college football.

One scout said he's still going to all of his "free agent schools" outside of the power conferences.

Marcus Yarns , one of seven FCS players at the combine, could have moved up to a bigger program for his last season .

He heard bigger programs were interested in him as part of a one-two punch at running back, meaning his snap count would decrease.

A former NFL front office staffer said there is a lack of comprehensive data on transfer portal strategy and success.