PHILADELPHIA -- Word that the Philadelphia Eagles were signing free agent quarterback Chase Daniel wasn’t surprising. The numbers were another matter.

According to ESPN’s Adam Caplan, Daniel’s three-year contract is worth $21 million with $12 million guaranteed. The deal can be worth as much as $36 million, with raises built in if Daniel starts more games.

The guaranteed money is a lot to pay for a backup quarterback. That raised immediate speculation that the Eagles plan to trade Sam Bradford, who just last week signed a two-year, $35 million contract.

A Bradford deal is not very likely, for a number of reasons. It is bad form to trade a player who just agreed to a contract with your team. Doing so would raise red flags for every free agent the team ever tried to sign.

More important than that, though, is the reason the Eagles signed Bradford to the new contract in the first place. He was the best option available to them at the most important position in the sport. That calculation was made knowing that Daniel was due to become a free agent.

The pressure on the Eagles would be immense if they moved on from Bradford and went with Daniel. And that pressure would lead to an explosion if Daniel, who has thrown 77 passes in his six-year NFL career, did not succeed as a starting quarterback.

Eagles coach Doug Pederson coached Daniel in Kansas City. The Eagles’ signing parallels Andy Reid’s signing of Pederson back in 1999. Reid had become head coach of the Eagles after serving as quarterbacks coach in Green Bay. He signed Pederson to a three-year, $4.7 million contract.

But Pederson was signed to start while Reid groomed the rookie quarterback he planned to draft that year. That turned out to be Donovan McNabb. Pederson started a total of nine games with the Eagles. He was released before the 2000 season after earning $3 million for his one season.

The money has changed dramatically since then. Daniel’s deal is worth five to nine times as much as Pederson’s 1999 deal was worth. But the pressure that comes with the money, and the job, hasn’t changed.

It is understandable, given Bradford’s injury history, that Pederson would want a reliable, familiar backup quarterback. But it is fair to question the wisdom of investing that much money and salary-cap space for an unproven backup quarterback.

The Eagles already had Mark Sanchez under contract. Sanchez will count $5.5 million under this year’s salary cap. He is now likely to be released, assuming the Eagles can’t trade him. That will save $3.5 million of cap space.

The length of Daniel’s contract suggests that the Eagles wanted to have some insurance in case Bradford doesn’t play well or is injured again. In the worst-case scenario, the Eagles would have Daniel for three years.

That is what they’re paying for. It’s a hefty price for a relatively unproven player.