Before the extension, Lockett was under contract for this year at a $13.7 million cap hit. Per Spotrac, Seattle had $9.5 million in cap space heading into 2021 campaign.
But Brady Henderson of ESPN reported that Lockett's extension should provide the Seahawks with some immediate cap relief:
"Lockett was set to have the third-largest cap hit of any Seahawks player in 2021 at $14.95 million. His extension lowers that number to around $7 million, a source told ESPN. That gives Seattle some needed breathing room against the cap and is one reason for the timing of Lockett's extension, which comes much earlier in the offseason than when the Seahawks typically do new deals for players who are under contract."
Shaving almost $8 million off the cap this season would leave the Seahawks with around $17 million in cap space, with that number increasing more once the team trims the roster to 51 players—though incoming rookies will take a bite out of the number.
It was unclear if the Seahawks would extend Lockett this offseason, with DK Metcalf nearing extension eligibility (he's under contract through the 2022 season). The wideout is going to get paid in a big way given his current career trajectory, leaving the Seahawks with a lot of future money going to the position.
But Lockett has remained productive. The 28-year-old caught 100 passes for 1,054 yards and 10 scores last season, setting a career high in receptions and tying a career high in touchdowns. It was his second straight year exceeding 1,000 receiving yards and his third straight with eight or more receiving touchdowns.
The Seahawks didn't want to risk losing Lockett after this season with the Kansas State product clearly in his prime. They are paying big money to keep him around.