While various franchise and transition player designations went about as planned Tuesday, the Eagles struck after the deadline with a surprising extension. Philadelphia doubled down on its investment in Sam Bradford, who was about to hit unrestricted free agency after a disappointing first season with the team. Bradford signed a two-year, $36 million deal to stay with the Eagles, and Adam Schefter reported that the contract will include a whopping $26 million in guarantees.

The initial reaction to this deal is, essentially, "Wait, really?" It's hard to envision a player who has struggled as much as Bradford has, even at a premium position, getting $18 million per year. Something seems fundamentally off. J.J. Watt's deal doesn't average $18 million per year. Julio Jones' contract doesn't get there. Tony Romo's extension is $18 million per season, but Romo had virtually infinite leverage and has been a far better quarterback than his NFC East counterpart.

I don't think it's a good deal for the Eagles, given Bradford's level of play during his pro career. What I do want, however, is to try to understand it. The Eagles could have locked up Bradford on a one-year deal for $20 million with the franchise tag. Instead, they chose to guarantee Bradford more than $6 million more as part of a two-year pact. Let's try to piece together the logic from Philly's perspective.

1. The Eagles need a quarterback.

It seems like all parties involved can agree on this. If Bradford hit free agency, the Eagles were going to be stuck with Mark Sanchez and McLeod Bethel-Thompson as the only signal-callers on their roster. Even if you make the case that Sanchez might not be all that much worse than Bradford (I think that's a fair argument), Eagles personnel chief Howie Roseman was going to bring in a third quarterback. That could have been (and still could be) via the draft, but more likely, it was going to be a veteran acquired in free agency.

If the Eagles wanted to add a quarterback, as much as I'm intrigued by this year's crop of quarterback free agents, Philly might not have seen many likable options. Kirk Cousins was franchised on Tuesday. Brock Osweiler might have a hush-hush deal to go back to Denver after Peyton Manning moves on. You can understand why the Eagles might not have found high-profile options such as Peyton or Robert Griffin especially appealing. Also, the Rams have publicly suggested that they aren't likely to trade Nick Foles, even if Philly were interested.

With new head coach Doug Pederson, it might have been a choice between Bradford and Chiefs backup Chase Daniel, whom Pederson saw on a daily basis as the offensive coordinator in Kansas City. Daniel has had buzz each time he has hit the free-agent market, and he should get a multiyear deal to serve as a backup somewhere, but he has thrown 77 regular-season passes in seven pro seasons. Daniel is certainly a high-variance option, but one person's variance is another's uncertainty, and NFL teams don't do well with uncertainty. Would the Eagles rather pay a former undrafted free agent whom most of the organization hasn't seen, such as Daniel, $6 million per year or give Bradford, a familiar face with the pedigree and athleticism of a former first overall pick, $18 million per season? If Daniel gets major reps and the Eagles crater, what's the fallout?

2. Bradford improved as the season went along.

The former Oklahoma star put on a much better showing after Philadelphia's Week 8 bye. Bradford posted a league-worst 29.6 QBR over the Eagles' first seven games of 2015, with an impressive second half against the Falcons and a three-touchdown day against Washington mixed with a series of disastrous performances. Although Bradford missed two games after the bye because of a shoulder injury, he nearly doubled his QBR and got up to 55.0 in his seven post-bye starts. That was good for 20th in the league. His raw numbers also improved dramatically:

Sam Bradford in 2015 Split Cmp Att Cmp% Yds Y/Att TD INT Before Bye 170 274 62.0% 1,766 6.4 9 10 After Bye 176 258 68.2% 1,959 7.6 10 4

Acknowledging Bradford's established reticence and limitations throwing downfield, those second-half numbers seem to point to the passer Bradford would have been expected to be in Philly, as a high-percentage, low-risk passer with limited upside. That guy probably isn't worth $18 million per year, but compare him to Alex Smith, who got $17 million per season on a four-year deal when the Chiefs re-upped him before the 2014 campaign. The Eagles might very well see Bradford as their Smith: a passer who can make safe, accurate throws and avoid giveaways. Remember: Bradford's bad first half wasn't a total shock, as he was coming off a long layoff because of injury.

I don't think relying solely upon Bradford's second-half numbers is the best way to project his future performance, but it's plausible that the Eagles leaned more heavily on those figures in estimating what Bradford will do in 2016 and beyond.

3. The open market could have earned Bradford just as much.

As much as the NFL combine is about evaluating and interviewing college prospects, it's also about talking to agents and evaluating the free-agent market-to-be. The Eagles -- and Bradford's representation -- were likely able to gain insight into what the marketplace would've held for Bradford, if he hit unrestricted free agency in the middle of March.

Sam Bradford did seem to find his form over the second half of 2015, which helped him entering free agency. Elsa/Getty Images

Part of that game is bluffing to create leverage, of course, but the Eagles might have wondered whether they would be able to compete with other suitors if Bradford were able to negotiate with 31 other teams. They paid a premium to lock up Bradford, but it's entirely possible that a quarterback-needy team such as the Browns or Rams would have been willing to shell out even more money to sign Bradford on a longer-term contract. (It seems crazy to include the Rams as a suitor, but this is the same franchise that offered Jeff Fisher's staff contract extensions. They love continuity!) Maybe the Eagles believed somebody was willing to offer Bradford, say, a three-year, $45 million deal with $30 million guaranteed. The Eagles would have preferred to see Bradford wade into free agency and find an unfriendly market before they brought him back on a one-year deal for less than the $20 million franchise tag, but that wasn't necessarily going to happen.

4. Philadelphia wanted to benefit in future years if Bradford succeeds in 2016.

That's the best explanation I can come up with for why the Eagles didn't franchise Bradford for one year at a haircut under $20 million. Even if Bradford didn't want to be franchised, the Eagles could have used the leverage from the franchise tag to lock him up on a two-year deal without having to worry about him hitting the free-agent market. The Eagles didn't use their tag on any other player, so it seems bizarre that they would guarantee Bradford an additional $6 million in this deal.

The structure of Bradford's deal hasn't been revealed, but that will likely tell us more about why the Eagles chose not to use the franchise tag. In the past, there have been quarterbacks who had massive amounts of "guaranteed" money that turned out to be modest amounts of truly guaranteed cash, and that might be the case here. It's unlikely Bradford truly has $26 million in fully guaranteed money coming as part of this deal.

The difference between those deals and Bradford's, though, has to do with the nature of Bradford's playing history. Most of the inflation in reports about guaranteed money comes with deals guaranteed for injury; that means a player is only guaranteed to receive the dollars if he gets hurt, and his team can choose to cut him if he's healthy but ineffective.

That might be part of the language in this deal, but the reality is "guaranteed for injury" means a lot more in a deal for Bradford than it does in one for, say, Eli Manning. Bradford has a lengthy injury history, and the chances that the Eagles are stuck paying an injured quarterback guaranteed money in 2017 are far greater with Bradford than they would be with a typical quarterback under the same contract.

That's what makes this deal so curious. The best-case scenario appears to be that the Eagles lock up an average quarterback at pretty close to market value for two years, and the worst-case scenario is that they're stuck paying a guy who is alternately injured and mediocre more than they need to in 2016 and 2017.

Few onlookers could have seen Bradford's 2015 and thought he was worth what the Eagles are paying, yet the team has signed on for another go-round. Then again, Bradford's four seasons with the Rams weren't especially impressive, and the Eagles (under Chip Kelly's control) traded for him anyway. As Bradford enters his seventh professional season, the Eagles will pay a premium for the privilege of hoping he finally breaks out.