It's because it's Sam Bradford.
Shady and D-Jax might have been expensive for their respective positions, but were proven commodities. Bradford hasn't really proven anything in 5 years, other than that he struggles to stay on the field
13 mil is about the 15th highest paid QB in the league right now. And thats before Wilson and Luck get their pay day's into the top 2 spots.
Add to that you'd have to think that if Bradford is really Chips guy and he's here to be our franchise, an extension will be forth coming that will lower that number, i mean i doubt we're giving up what we have to get Bradford only to put him into a QB friendly offense and let him walk in 12 months time.
I dont like that it's Bradford either. But the reality is Chip seems to think he can be our franchise QB, and 13 mil for a Franchise QB is not big money. And it doesnt matter what you or i think of Bradford, the guy doing the deals and coaching the team says he's the man.
10 mil for an RB is insane money. 10-11 mil for WR's in Chips system is insane. All three of those guys shattered their seasons best in Chips system. I think Chip feels like he doesnt need to pay top talent in those positions because his scheme doesnt need elite talent to get production. So he saves money there, invests it in the OL, QB and Defense. And backs his system to handle the other stuff.
You can disagree with Kelly about whether constructing a team like this can lead to success and whether Bradford is a franchise guy, there is plenty including myself who have those doubts, but that's the way he wants to build his team. He'll succeed or fail on his terms i guess.