An interesting thing to consider here is how much a quarterback benefits from staying all 4 years in college. Now, if it's simply about getting a big money contract, I'm sure Jimmy could care less, but I have to think a kid like Clausen genuinely cares about being a great QB at the next level. If that is the case, he'll make plenty of money in his career.
Look at the the successful QB's in the NFL: Manning, Brady, Brees, Matt Ryan, McNabb, Joe Flacco, Carson Palmer, Philip River to name a few.
The common denominator with all of these folks is that they returned and played 4 years of college. The got stronger both mentally and physically and, from a maturity standpoint, were ready to have great careers. Manning, Rivers, McNabb, etc. probably could have come out after their Jr. years and easily been 1st rounders, but, instead, chose to stay.
On the other hand look at Jamarcus Russel, Ryan Leaf, etc. who have struggled mightily. In fact, I can't think of any Quarterbacks who came out early and succeeded long-term (The Jury is still out on Sanchez and Stafford) Now, it may be unfair to compate Jimmy to Jamarcus and Leaf because I have to think his head is screwed on much tighter, but it's an interesting thought.
The best example is proably a kid like Stafford in Detroit. He got the contract he wanted. He'll be rich forever. But I find it hard to believe he will ever have a successful NFL career in Detroit where he will forever be rushed and put into a very difficult decision.
Forget about the Rookie contract Jimmy, return for your Sr. year.
