A good number of college QBs that are considering a transfer are very good college QBs. That doesnt mean they will be good NFL QBs, but with one more great year in college they can imagine that they would be drafted and get a big payday (like Burroughs or Hurt who were mediocre at the former college and became highly desired draft choices in their senior years after transferring).
Nothing was contradictory. Some college QBs are decent college QBs but are on the NFL bubble for various negative reasons and they desperately need a very good senior season to showcase themselves to the NFL.
Those are the guys dumber than dirt if they do not transfer and they simply sit on their azzzzes for a year just because they want to play for the MINNESOTA MOLES or the ILLINOIS FIGHTING IDIOTS or the INDIANA MULESKINNERS.
To ruin your NFL chances in order to hope and pray for a Spring season that aint gonna happen is stupid beyond belief if you think you might have a shot at the NFL. Even if it is a remote chance at the NFL.
Not playing at all for a full year guarantees your chances of the NFL are gone (unless you are a superstar).
You say these QBs are just decent but a couple of paragraphs later you are talking about them thinking of their NFL prospects. These seem to be contradictory ideas unless the players have delusions of grandeur.