The quarterback expected to succeed Peyton Manning in Denver is leaving the Broncos for the Texans

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The biggest domino in NFL free agency has fallen, according to reports.

NFL Network's Rand Getlin first reported that Brock Osweiler, the 25-year-old backup expected to succeed Peyton Manning in Denver, is signing with the Houston Texans.

According to ESPN's Adam Schefter, the deal is a monster: four years, $72 million.

As CBS' Jason La Canfora pointed out after the news broke, the Broncos, who had offered a three-year, $45 million to Osweiler, were only willing to go so high for a quarterback who's only started seven games.

For the Broncos, their quarterback position is in a dire state with Manning and Osweiler gone. NFL Network's Ian Rapoport previously reported that the Broncos would pursue Colin Kaepernick if Osweiler signed elsewhere.

Now, Schefter reports that Robert Griffin III is an option:

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With Brock Osweiler off to Houston, RGIII is on Broncos' list of replacement quarterbacks, per source. Could be visiting Denver.

With Osweiler moving on, the NFL will be in a scramble to grab available, competent quarterbacks.

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