I found the phrase in the 2008 Swanton Bulldogs Defensive Line Manual:
Relentless Pursuit of the Football. Swarm and Stick.
And also at bobcatnation.com:
EWU has stockpiled speed and young talent on defense and the departure of stalwarts like Ronnie Hamlin and Evan Day will give way to much more athletic playmakers who can swarm and stick.
Swarm suggests many players moving in a body or converging onto some place or someone, but I can’t tell which of these, if any, it means here. And what about stick?