FOXBOROUGH, Mass. -- The New England Patriots have tweaked the contract of starting right tackle Sebastian Vollmer, decreasing the percentage of plays he must play in order to earn up to $2 million in incentives, according to league sources.

Vollmer will earn $1 million if he plays 70 percent of the Patriots' offensive snaps and $2 million if he earns 80 percent of the team's offensive snaps.

Under previous terms of the deal, Vollmer was set to earn $1 million if he played at least 80 percent of the offensive snaps and $2 million for playing 90 percent of the offensive snaps. This money can be earned on top of his $2 million base salary for 2014.

In addition, Vollmer is due a $1 million roster bonus on the third day of the 2015 league year if he plays 70 percent of this year's offensive snaps, down from 80 percent before the restructure.

The restructure results in a prorated cap charge of $333,333.33 over each of the next three seasons.

Through nine games this season, Vollmer has played in 91.2 percent of the offensive snaps, rotating on occasion with Marcus Cannon, the team's top reserve lineman who has also taken snaps at left tackle.

The Patriots signed Vollmer to a four-year deal last offseason, locking up a player that has been a fixture on their offensive line since being drafted by the team in 2009.